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Sustainable Agriculture Research and Education in the Field: A Proceedings (1991)

Chapter: PART TWO: RESEARCH AND EDUCATION IN THE WESTERN REGION

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Suggested Citation:"PART TWO: RESEARCH AND EDUCATION IN THE WESTERN REGION." National Research Council. 1991. Sustainable Agriculture Research and Education in the Field: A Proceedings. Washington, DC: The National Academies Press. doi: 10.17226/1854.
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PART TWO

Research and Education in the Western Region

Suggested Citation:"PART TWO: RESEARCH AND EDUCATION IN THE WESTERN REGION." National Research Council. 1991. Sustainable Agriculture Research and Education in the Field: A Proceedings. Washington, DC: The National Academies Press. doi: 10.17226/1854.
×
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Suggested Citation:"PART TWO: RESEARCH AND EDUCATION IN THE WESTERN REGION." National Research Council. 1991. Sustainable Agriculture Research and Education in the Field: A Proceedings. Washington, DC: The National Academies Press. doi: 10.17226/1854.
×

6

Comparative Study of Organic and Conventional Tomato Production Systems: An Approach to On-Farm Systems Studies

Carol Shennan, Laurie E. Drinkwater, Ariena H. C. van Bruggen, Deborah K. Letourneau, and Fekede Workneh

This chapter describes an on-going study of existing organic and conventional tomato production systems in California supported by the low-input sustainable agriculture (LISA) program of the U.S. Department of Agriculture (USDA). The goal of the project is to investigate various soil, plant, and animal processes that function within the agroecosystem as they respond to different amounts and types of inputs. In addition, economic data are being collected to document the costs and trade-offs associated with the various management systems. Such information can then be used to help assess the long-term sustainability of these production systems in terms of productivity, efficiency of resource use, reduced inputs and off-farm impacts, and maintenance of the resource base, notably, the soil. The project was initiated in 1988, and the first-season data were collected in 1989. Because this project represents a relatively unique design for comparing different production systems, the major focus of this chapter will be to discuss and evaluate the approaches taken in developing this on-farm study.

TERMINOLOGY

For this study, farms are considered organic when the management strategy for at least the past 3 years has emphasized reliance on biological processes. Plant nutrients are supplied primarily through the use of green manures, organic soil amendments, or both, and synthetic fertilizers and pesticides are not used. Farms that use synthetic fertilizers, pesticides, or both and that do not add organic soil amendments (other than crop residues) are considered conventional. Several sites are intermediate between these

Suggested Citation:"PART TWO: RESEARCH AND EDUCATION IN THE WESTERN REGION." National Research Council. 1991. Sustainable Agriculture Research and Education in the Field: A Proceedings. Washington, DC: The National Academies Press. doi: 10.17226/1854.
×

two extremes and are referred to as transitional. Most transitional farms fit into one of two categories: (1) farms that have grown crops organically for less than 3 years, or (2) organically managed farms that do not have a soil management program that includes the regular use of organic soil amendments or green manures. Although these management designations are convenient, they are still somewhat artificial, since farming practices in reality fall along a continuum rather than into discrete groups. For example, several of the conventional farmers did not spray insecticides in 1989, and in 1990 one conventional farmer used legume cover crops for nitrogen fertility but will still use synthetic fertilizers and insecticides as needed. This problem of farm categorization will be discussed further later in the chapter.

BACKGROUND RATIONALE

California currently leads all other states in vegetable production (Scheuring, 1983). In the Central Valley alone, the annual tomato acreage (215,000 acres) is valued at $400 million, while other vegetables, predominantly melons, occupy 245,000 acres with a value of $540 million (California Farmer, 1987). Vegetable production systems utilize large quantities of inputs such as pesticides, fertilizers, and irrigation water; therefore, a decrease in inputs in these systems could have a profound effect on California's agroecosystems as a whole. Fresh market tomato production systems have been targeted for the present study, because production from California's Central Valley represents 30 percent of the total U.S. fresh market tomato production, and most importantly, a variety of management systems exist in this region, including long-term organic tomato production.

The widespread adoption of intensive conventional agriculture in California has been accompanied by the appearance of symptoms of poor soil structure (Chancellor, 1977). One symptom is decreased porosity, which can inhibit water infiltration, root penetration, and, thus, plant nutrient and water acquisition (Oades, 1984; University of California, Davis, 1984). To compensate for deteriorated soil structure or poor root development, farmers may increase applications of water, nitrogen, or both (Chancellor, 1977; E. M. Miyao, Yolo County Farm Advisor, personal communication, 1990), which, in turn, raises the potential for leaching of nutrients into groundwater (Freidrich and Zicarrelli, 1987). Furthermore, continuous cropping with vegetables and the decline in soil structure have been accompanied by increased losses caused by root diseases, such as phytophthora root rot of tomatoes (University of California, Oakland, 1985). Moreover, excessive soil nitrogen and water application have been implicated in the increased susceptibility of tomatoes to some pathogens (Ristaino et al., 1988; Schmitt-

Suggested Citation:"PART TWO: RESEARCH AND EDUCATION IN THE WESTERN REGION." National Research Council. 1991. Sustainable Agriculture Research and Education in the Field: A Proceedings. Washington, DC: The National Academies Press. doi: 10.17226/1854.
×

henner and Canaday, 1983; van Bruggen and Brown, in press), further compounding the problem.

The beneficial effects of increased organic matter on soil structure and biology have been well documented (Chaney and Swift, 1984; Oades, 1984; Tate, 1987; Tisdall and Oades, 1982). Suppression of several plant diseases by certain soils has been attributed to high levels of microbial activity (Chen et al., 1988), and there is also evidence that use of green manures can decrease crop disease severity (Cook, 1984). Slow release of nitrogen from organic sources is reputed to lead to lower nitrate concentrations in the soil, which could potentially reduce losses via leaching, in addition to ameliorating some root disease problems.

Taken together, these considerations suggest that management systems in which an effort is made to improve soil organic matter may help alleviate many of these problems. Most of the studies cited, however, refer to climates where organic matter turnover is relatively slow and increased levels can be maintained over time by appropriate management (Johnston, 1986; Reganold, 1988). Little information is currently available for semiarid irrigated systems in which high temperatures and frequent water applications favor rapid organic matter turnover. Long-term studies of cover-cropped orchard systems in California concluded that it is not possible to increase organic matter in this environment significantly (Proebsting, 1952, 1958). A corollary of this has been the assumption, therefore, that soil structural properties similarly could not be improved by efforts to enhance organic matter in California soils. In contrast, work in progress (Groody, 1990; C. Shennan, C. Griffin, and T. L. Pritchard, unpublished data) suggests that leguminous winter cover crops may improve the structural characteristics of soil and that various combinations of cover crops, tillage, and gypsum applications can improve orchard soils (Moore et al., 1989). Earlier work by Williams and Doneen (1960) and Williams (1966) also demonstrated the beneficial effects of a variety of cover crops on water infiltration in a Central Valley soil. However, it should be noted that, in general, the links between specific management practices, changes in soil properties, and their effects on plant growth have not been well established (Karlen et al., 1990).

In conventional farming systems, levels of damage caused by insects remain high on many crops, even doubling in the past 30 years in some cases, despite continual development of sophisticated crop production technologies (Bottrell, 1980). Pesticides, fertilizers, and cropping patterns can drive pest population dynamics and modify damage to crops in various ways (Altieri and Letourneau, 1982; Bethke et al., 1987; Fery and Cuthbert, 1974). Insecticides can rapidly control pest species or can cause reactive outbreaks (Pedigo, 1989). Vegetational diversity in space and time may enhance the maintenance of natural enemies (Altieri and Letourneau, 1982),

Suggested Citation:"PART TWO: RESEARCH AND EDUCATION IN THE WESTERN REGION." National Research Council. 1991. Sustainable Agriculture Research and Education in the Field: A Proceedings. Washington, DC: The National Academies Press. doi: 10.17226/1854.
×

and for many crops, increased plant nitrogen content is associated with increased attractiveness to insect herbivores (Leath and Ratcliffe, 1974; Letourneau and Fox, 1989). Each of these factors can be influenced by farming practices that can be expected to differ among organic and conventional systems.

GOALS OF THE PROJECT

It is clear from the preceding discussion that crop yield, the most commonly measured attribute of agroecosystems, represents the outcome of complex interactions among soil, plant, pest, disease, and environmental and management parameters. It is the goal of this project to determine the impact of different combinations of production practices (ranging from organic and transitional to conventional) on various components of the agroecosystem.

More specifically, management practices are being documented, and inputs, outputs, and a variety of soil, plant, pest, and disease parameters are being quantified for each site. A variety of questions are being addressed. For example, do soils on organic and conventional farms differ with respect to nitrogen availability, structural properties, or microbial activity? If so, are these differences reflected in patterns of plant growth and nutrient acquisition? Are the incidence and severity of root diseases or insect pests affected by these soil, plant, or management characteristics; if so, which ones are the most important? Does the structure of arthropod communities associated with the tomato crop change with different management practices; if so, are these changes reflected in differences in crop damage levels or yield loss because of insect pests? Are soils from organic farms more able to suppress the growth of root pathogens, and does this ability correlate with particular soil characteristics such as microbial activity or nitrate levels? These and other questions will be answered by the use of a hierarchical approach in which data are collected both at the field and individual plant levels.

The project's main focus is to develop an understanding of the biological and ecological characterisitics of the production systems. From a practical point of view, however, it is critical to obtain sufficient information to provide a context for economic assessment of the different strategies used. To this end, enterprise budgets are being derived for each tomato production system, and the extent and nature of any financial gains or losses resulting from decisions to reduce, or cease, application of chemical fertilizers and pesticides will be evaluated. Since the economic component of the study is at a very early stage of development, it will not be discussed further.

Suggested Citation:"PART TWO: RESEARCH AND EDUCATION IN THE WESTERN REGION." National Research Council. 1991. Sustainable Agriculture Research and Education in the Field: A Proceedings. Washington, DC: The National Academies Press. doi: 10.17226/1854.
×
WHY AN ON-FARM STUDY?

A great deal of agricultural research has been based on replicated factorial experiments conducted at experiment stations or in growers ' fields. In these experiments the effects of varying one or two factors are monitored while steps are taken to maintain all other factors constant. In this way the potential for the factors under study to affect processes of interest is clearly established. However, since the ecosystem processes of interest can potentially respond to, and interact with, many environmental and management factors simultaneously, it is not feasible to approach the study of integrated systems by use of factoral experiments. Furthermore, since there is little or no information available on organically managed vegetable production systems, it was not clear a priori what factors or management practices should initially be targeted. It seemed logical, therefore, to document the characterisitics and functioning of selected complete management systems before attempting to isolate components of these systems for more detailed examination. Significant relationships identified from the systems study can then be targeted in separate experiments to elucidate the mechanisms that are operating.

Having decided upon a systems comparison, the question remains as to whether it is preferable to simulate the systems of interest in some kind of replicated experiment or to study existing farm operations. A number of farming system comparisons have taken the first approach by creating experimental organic, biological, integrated, or conventional treatments to simulate the various production systems of interest (Culik et al., 1983; Daamen et al., 1989; Doran et al., 1988; Sahs and Lesoing, 1985; Steiner et al., 1986; Vereijken, 1989; Weisskopf et al., 1989; Zeddies et al., 1986; see also R. Janke, J. Mountpleasant, S. Peters, and M. Bohlke, “Long-Term Low-Input Cropping Systems Research, ” this volume). This approach offers a number of advantages by allowing whole management systems to be studied while at the same time reducing the influence of potentially confounding variables such as soil type, surrounding habitat, and microclimate and by allowing for true replication of treatments. A further advantage of this approach is that the experimenters have full control over all management decisions. What is often the case, however, is that because of resource limitations, there must be a trade-off between the scale of the experiment and the number of replications. The sizes of the experimental plots is generally reduced to less than typical field scale to allow for reasonable replication. Alternatively, if field-size plots are chosen, then there may be little or no replication (Vereijken, 1989; Weisskopf et al., 1989).

Deciding upon the scale of experimental plots is a very important consideration, since scale can have significant impacts on the results that are obtained and their interpretation. This is particularly true for studies of

Suggested Citation:"PART TWO: RESEARCH AND EDUCATION IN THE WESTERN REGION." National Research Council. 1991. Sustainable Agriculture Research and Education in the Field: A Proceedings. Washington, DC: The National Academies Press. doi: 10.17226/1854.
×

mobile insects (Kareiva, 1983; Letourneau and Fox, 1989) and properties that have distinctly patchy distributions, such as root disease incidence or severity (Madden, 1989). Further disadvantages of the experimental approach include the fact that the data obtained are from only a single location and may not be readily extrapolated to other sites. Also, one set of practices is used to represent a type of production system, whereas in reality, there are usually many variations on a central theme.

The second approach to studying existing farm operations also brings its own set of advantages and disadvantages. Indeed, the two approaches are regarded as complementary since they can provide different kinds of information. First and foremost among the assets of the on-farm approach is that the systems under study are realistic for the present time. They represent combinations of practices and decisions made by farmers who are surviving in a world full of practical and economic constraints. Moreover, when the information is derived from multiple locations and management combinations, the robustness of any relationships that can be identified is increased. Of particular importance for this study is the fact that multiple sites could be selected that have been under organic management for various lengths of time—some for many years.

In other studies a transition period has been observed following a switch to organic production methods, during which time yields may be reduced, nutrient availability may be limited, and pest problems may be increased (see the chapter by R. Janke and colleagues in this volume). Presumably, this period represents the time required for the system to attain some kind of dynamic equilibrium with respect to soil biological changes (Paul, 1984; van der Linden et al., 1987) and, perhaps, insect and weed population dynamics. Thus, the first few years of studying experimental organic systems will be spent describing the transition process. Although this is clearly of great interest, in this study the major focus is the potential for organic practices to affect attributes of the agroecosystem over the long term. By observing existing farms that have operated organically for various lengths of time, the present study provides a mechanism for doing this from the outset.

Finally, working on existing farms provides an avenue for considerable interaction and information exchange between farmers and researchers. In particular, the researchers become much more familiar with the kind of decisions and compromises farmers have to make and the issues they feel are most important. Farmers, in turn, can benefit from opportunities to communicate their ideas and concerns directly to the researchers and have access to research results. Some of the approaches taken in this study to maximize this kind of two-way communication are described later in this chapter.

The disadvantages associated with comparisons of existing production systems include the need to account for potentially confounding variables

Suggested Citation:"PART TWO: RESEARCH AND EDUCATION IN THE WESTERN REGION." National Research Council. 1991. Sustainable Agriculture Research and Education in the Field: A Proceedings. Washington, DC: The National Academies Press. doi: 10.17226/1854.
×

and the extra work load associated with the more extensive data collection this approach requires. Climate, soil type, surrounding habitat, planting date, crop cultivar, and other management details unrelated to those of interest will vary among locations and therefore must be measured and included in subsequent analyses, when appropriate, to avoid misinterpretation of the data. Provided that sites can be selected such that a similar range of these variables exists within each of the broad management categories (e.g., organic and conventional), then the effects caused by management comparisons of interest, such as organic versus inorganic nitrogen input, can be separated from those caused by extraneous variables such as soil type or planting date.

Because of these considerations and the complexity of farm systems, site selection involves considerable time and effort, as does the collection of information and sampling from multiple locations and coordination of these activities with each of the farmers in turn. Finally, the fact that the investigators are not in control of the management decisions may be an asset or may prove to be problematic. On the one hand, the farmers are most knowledgeable about their fields and production options, and any decisions they make are based on the realities of physical, biological, and economic constraints. On the other hand, the decisions that are made may not be in the best interest of the project. For example, based on market considerations, a grower may decide to change the planting date, not plant the crop of interest, or cease managing a field part way through the season. An ability to compensate farmers financially for modifying their plans to accommodate the research project may help avoid such problems. While these potential problems can increase the risk and difficulty of conducting the research, none of these problems are insurmountable, and the rewards from studying existing farming systems outweigh the disadvantages.

METHODOLOGICAL CONSIDERATIONS

Selected components of the agroecosystem have been emphasized in previous studies on existing farms, such as specific insect abundance (Altieri and Schmidt, 1986), soil properties (Bolton et al., 1985; Doran et al., 1988; Maidl et al., 1988; Reganold, 1988; Reganold et al., 1987), or economics (Goldstein and Young, 1988), but interdisciplinary studies such as the one being conducted with tomatoes in California have rarely been attempted. Two excellent examples of integrated interdisciplinary studies are the comparison of organic and conventional farms in the Midwest United States by Lockeretz and coworkers (1981) and the study of interactions among soil properties, cultural practices, pathogens, and crop yield in existing Australian wheat farms by Stynes and colleagues (1979, 1981, 1983) and Veitch and Stynes (1979, 1981).

Suggested Citation:"PART TWO: RESEARCH AND EDUCATION IN THE WESTERN REGION." National Research Council. 1991. Sustainable Agriculture Research and Education in the Field: A Proceedings. Washington, DC: The National Academies Press. doi: 10.17226/1854.
×

The advantages of conducting integrated interdisciplinary studies of farming systems are numerous. A distinction is made between integrated interdisciplinary and multidisciplinary, because in many cases the latter results in two or more distinct facets of a system being investigated, with few connections being made between them. Integration of the disciplinary approaches can increase the resource use efficiency of the work, since much of the data collected is often common to many areas of investigation. More importantly, however, interactions among different components of the system can only be studied realistically in an integrated interdisciplinary framework. For example, interactions occur among soil properties, nutrient cycling, disease development, plant growth, susceptibility to insect damage, and economic return. To understand these interactions, it is critical that relevant data be collected in a manner that is useful to soil scientists, horticulturists, pathologists, entomologists, and economists. This requires considerable time in planning and discussion, a willingness to compromise, and respect for each investigator's research goals.

Miller (1983), while acknowledging the necessity for team approaches to studying complex systems, has identified psychosocial and institutional barriers to truly integrated interdisciplinary research in the context of the development of integrated pest management and forest management programs. In his study, he found that the researchers had only rudimentary collaborative skills themselves and very little institutional support or incentive to form effective collaborations. In developing the study of tomatoes in California described here, many of the problems Miller identified were encountered. The need for continual dialogue and coordinated decision making throughout the project must be reemphasized. The outcome of this process is a project that is truly cooperative, representing a synthesis of ideas from researchers with diverse backgrounds.

Site Selection

The most important consideration in choosing study sites for the project described here was to minimize confounding variables. Clearly, what constitutes a confounding variable depends on the questions being addressed. For example, if the question relates to the role of production practices in affecting soil properties, the actual location of a farm may be of little importance, whereas parent soil type is critically important. However, if interactions between soil properties and plant growth are being examined, climatic variability among locations will influence the analysis and interpretation of the data that are collected. For an entomologist, the major variables of concern are surrounding habitat, microclimate, and field size, whereas for a plant pathologist, the presence of the relevant pathogens in fields of all management types is of primary importance.

Suggested Citation:"PART TWO: RESEARCH AND EDUCATION IN THE WESTERN REGION." National Research Council. 1991. Sustainable Agriculture Research and Education in the Field: A Proceedings. Washington, DC: The National Academies Press. doi: 10.17226/1854.
×

While differences in preferred selection criteria exist among the disciplines, it became obvious during the development of the tomato project that a few general criteria formed a reasonable compromise. Primary consideration needed to be given to locating farms such that the overlap among the different management types, in terms of geographic location, local climatic conditions, and range of parent soil types, was maximized.

Initially, two important vegetable-producing regions were considered as study areas: the central coastal valleys of California, which produce mainly cool season vegetables, and the Central Valley, where warm season vegetables are produced. Based on the above criteria, site visits and a questionnaire were used to gather information on organic and conventional vegetable producers in both regions. The coastal region was found to have favorable characteristics for some of the project's objectives, most notably, varying levels of a potentially serious root pathogen of lettuce among different types of management systems. However, several problems existed that made this region less suitable for this kind of interdisciplinary study. Conventional and organic sites were geographically separated and experienced very different local climatic conditions. Furthermore, most organic farms were situated in isolated valleys away from other forms of agriculture. In this case, it would be difficult to separate out the effects caused by isolation and climate differences from those caused by management. Indeed, one viewpoint often stated is that organic farms require this type of isolation from other agricultural fields in order to avoid insect pest problems, although there is little evidence in the literature to support or refute this contention.

In contrast, in the Central Valley there was some overlap in the locations of organic and conventional sites, and while there was a climatic gradient, it was relatively slight. Furthermore, all of the organic farms in this area had agricultural neighbors, and some were surrounded by large agricultural fields. This attribute is essential if findings from the study are to be used to make inferences regarding the impact on farms in intensively cultivated areas where organic or reduced chemical input farming is adopted.

The selection of specific sites required a compromise among members of the different disciplines. All members of the research team ranked the sites in order of preference based on priorities related to their particular research interest. In this way, the sites that were most important for each discipline were sampled by the entire team. Finally, additional sites were selected for study by members of individual disciplines to address specific questions. This approach seemed like a realistic compromise, achieving the advantages of both the integrated interdisciplinary approach on a majority of sites while also providing a degree of autonomy to allow sampling methods and selection criteria for each research component to be more rigorously tested. For example, additional conventional fields were selected to be paired

Suggested Citation:"PART TWO: RESEARCH AND EDUCATION IN THE WESTERN REGION." National Research Council. 1991. Sustainable Agriculture Research and Education in the Field: A Proceedings. Washington, DC: The National Academies Press. doi: 10.17226/1854.
×

with nearby organic sites for measurements of arthropod community structure but were deemed unsuitable for extensive soil analysis because of large differences in field slopes between the sites.

Working with Farmers

During the initial contact, the project was described and growers were asked about their willingness to participate in the study. After the final selection of sites, all those who decided to cooperate in the study were mailed a letter that described the measurements that would be made and identified the specific field to be sampled. Most information on farm characteristics and production practices was collected orally by the project team members. In addition, data sheets were provided to growers to facilitate record keeping of irrigation applications, pest control, and tillage operations.

Contact is maintained with the cooperating growers on a regular basis, usually through letters and by telephone, to keep them informed of the study's progress. Some growers who are very interested in the project ask more questions about results and also serve as sounding boards for the research team's ideas. Recently, all cooperating farmers were provided with a copy of the progress report and invited to a meeting to discuss the preliminary results and to solicit their input and comments for the future.

ANALYTICAL APPROACHES

As discussed previously, two different approaches have generally been used to compare different farming systems. Either existing organic and conventional farms have been compared in the same general area (Lockeretz et al., 1981; Niederbudde and Flessa, 1989; Niederbudde et al., 1989; Reganold, 1988; Reganold et al., 1987; Sengonca and Bruggen, 1989) or different farming systems have been experimentally developed side by side (Daamen et al., 1989; Steiner et al., 1986; Vereijken, 1989; Vereijken and Spiertz, 1988; Weisskopf et al., 1989; Zeddies et al., 1986; see also Janke et al., this volume). With few exceptions (notably, Lockeretz et al. [1981] for comparison of existing farms and Janke et al. [this volume] for experimental systems), the number of replications included in these studies was limited or nonexistent (Daamen et al., 1989; Niederbudde and Flessa, 1989; Niederbudde et al., 1989; Reganold, 1988; Reganold et al., 1987; Sengonca and Bruggen, 1989; Vereijken, 1989; Weisskopf et al., 1989; Zeddies et al., 1986), and the data were subjected to minimal statistical analyses.

For this study, complete data sets were obtained for 8 sites in 1989, and selected measurements were made on 10 additional sites to address specific questions (Table 6-1 provides a breakdown of sites by discipline). The term site rather than farm is used since the sampling unit was a field, and in one

Suggested Citation:"PART TWO: RESEARCH AND EDUCATION IN THE WESTERN REGION." National Research Council. 1991. Sustainable Agriculture Research and Education in the Field: A Proceedings. Washington, DC: The National Academies Press. doi: 10.17226/1854.
×

Table 6-1 Breakdown of Data Collection in 1989 by Number of Sites

Number of Sites

Data Collected

≈60*

Farming practices

18

General soil characteristics

13

Detailed soil sampling (20 samples/site); analysis of nitrates, ammonium, nitrogen mineralization, aggregate stability, organic carbon

12

Disease assessment (corky root, Phytophthora), microbial activity

12

Insect diversity, damage assessment

8

Complete sampling by members of all disciplines

6

Water use, soil moisture profiles

16

Economic analysis

* The growers at the 60 sites who were interviewed consisted primarily of organic, transitional, and conventional mixed vegetable producers. Selected representative large-scale processing and fresh market tomato producers were also included in the survey.

case two separate fields in different locations belonging to one farm were each used as study sites. Field-level data were collected to describe the sites in terms of basic attributes (e.g., parent soil type and texture and surrounding habitat), management inputs (e.g., irrigation, fertilizer, cover crop biomass and nitrogen content, manure or compost, pesticides, and labor), and incidence of communities of associated pests and beneficial organisms. To compare community structure and pest and pathogen incidence among the different management categories more rigorously, efforts were made initially to pair each organic or transitional site with a conventional site on the basis of geographic proximity and, thus, microclimate similarity and shared source pools of colonizing pests.

Various plant, soil, disease, and pest damage parameters were also measured at 20 locations within each field (individual plant level). These data will be subjected to various multivariate analyses, as described below, to determine which factors contribute most to explanations of any major differences observed among farming systems. This approach has been successful in a variety of other studies, for example, in plant pathology (Ratkowsky and Martin, 1974; Thomas and Hart, 1986; Wallace, 1978), community ecology (Gauch, 1982; Pfender and Wootke, 1988; Widden, 1987), soil science (Nolin et al., 1989; Stynes and Veitch, 1981, 1983; Stynes et al., 1979, 1981; Veitch and Stynes, 1979, 1981), and entomology (Baumgartner et al., 1985).

Suggested Citation:"PART TWO: RESEARCH AND EDUCATION IN THE WESTERN REGION." National Research Council. 1991. Sustainable Agriculture Research and Education in the Field: A Proceedings. Washington, DC: The National Academies Press. doi: 10.17226/1854.
×
Sampling Techniques and Variables Measured

For a general description of the selected sites, three or four composite soil samples (composed of 20 systematic subsamples at depths of 8 inches) were collected from each site before the growing season. The following parameters were measured: percent sand, silt, and clay; pH and cation exchange capacity; and concentrations of nitrogen, phosphorus, potassium, calcium, magnesium, sodium, and boron.

During the tomato growing season (at fruit set), 20 individual soil samples were taken from each site. The sampling area varied from about 0.13 to 0.5 acres, depending on the number of rows planted to the same cultivar (as determined by the individual growers). Stratified random sampling was used to take into account the potential patchiness of the variables measured. Each sampling area was divided into 20 blocks, with one random sample taken from each block. Microbial activity (Schnuerer and Rosswall, 1982), water-stable aggregates (Kemper and Rosenau, 1986), organic carbon content (Nelson and Sommers, 1975), available nitrogen (nitrate and ammonia in potassium chloride extracts), nitrogen mineralization rate (Waring and Bremner, 1964), and Phytophthora parasitica populations (using the leaf baiting technique described by Tsao [1983]) were determined for each soil sample. Soil pH (in potassium chloride), electrical conductivity, total nitrogen content, and percent clay were determined on four composite samples from each field. At the green fruit stage, 18 inches of the tomato row (usually, approximately one plant) was uprooted at each of the same 20 locations where soil samples were previously taken. Total nitrogen in the tissue, shoot and fruit dry weight, insect injury (visual scoring of feeding signs of flea beetles, thrips, chewing insects, and leaf miners), and root rot severity scores (corky root and phytophthora root rot) were determined for each plant sample.

Pest and beneficial insects were sampled primarily by using malaise traps (flying insects) and vacuum collectors (insects on the tomato plants) for population and community comparisons. Predation and parasitism rates of pest species were assessed by baiting plants with prey and monitoring the degree of predation and parasitism of the baits.

Statistical Analysis

Initial statistical analysis of the field level data will consist of the derivation of descriptive statistics for each variable by management type (organic, conventional, and transitional), pesticide use, cultivar, and planting date. All variables will be checked for normality, and nonnormal variables will be transformed. Principal component analysis will be used to provide a first indication of the parameters that explain most of the variability among

Suggested Citation:"PART TWO: RESEARCH AND EDUCATION IN THE WESTERN REGION." National Research Council. 1991. Sustainable Agriculture Research and Education in the Field: A Proceedings. Washington, DC: The National Academies Press. doi: 10.17226/1854.
×

sampling sites on the different types of farms. To test whether the management groupings used reflect natural groupings based on the measured soil, plant, disease, and insect damage parameters, cluster analysis will be performed. In addition, multivariate analysis of variance (MANOVA) will be used to address the question of whether there are significant differences between farm types or pesticide use based on the measured parameters. MANOVA will also be used to identify and compensate for potential confounding factors such as planting date, soil texture, and cultivar.

The interrelationships between soil parameters will be examined by principal component analysis by using correlation matrices. Correlation rather than covariance matrices will be chosen to avoid bias caused by the widely different scales of the variables measured (Stynes et al., 1979). Plant yield and disease will then be regressed on the major soil components identified in the principal component analysis. In a similar manner, insect damage data will be regressed on the major components obtained from a principal component analysis based on soil and plant nitrogen data. Finally, all plants will be classified into two categories (healthy or diseased) with respect to corky root or Phytophthora spp., and then discriminant function analyses will be performed to determine whether sampling locations with healthy or diseased plants differ significantly in regard to various soil and plant characteristics (Afifi and Clark, 1984; Thomas and Hart, 1986). This analysis will also enable identification of the relative contributions of each soil and plant variable to the classification and to predict whether a plant growing in soil with a particular set of characteristics is more likely to become diseased than one growing in soil with a different set of characteristics. Similar discriminant analyses will be carried out to distinguish between sampling locations with and without various arthropods.

PRELIMINARY RESULTS AND EVALUATION
Site Selection

When scale-related farm characteristics such as total acreage, field size, crop mix, and marketing strategy were considered, it became clear that two different types of tomato growers exist in this region and cross the management designations of organic, transitional, and conventional as defined previously. Theoretically, any size farm could fall into all three management designations, ranging from small-scale mixed vegetable producers to large-scale tomato growers producing either “green-gas” (fresh market varieties harvested while fruit are still green) or processing (for example, machine-harvested varieties selected for processing into tomato sauce, tomato paste) tomatoes. At present, however, the project has

Suggested Citation:"PART TWO: RESEARCH AND EDUCATION IN THE WESTERN REGION." National Research Council. 1991. Sustainable Agriculture Research and Education in the Field: A Proceedings. Washington, DC: The National Academies Press. doi: 10.17226/1854.
×

not located any long-term, large-scale organic tomato producers, although some are currently in the transitional stage. The smaller-scale conventional mixed vegetable production systems have much in common with the organic systems, such as scale, crop mix, and reliance on direct marketing, but they are similar to large-scale systems with regard to the methods of soil management and pest control (Figure 6-1).

Sixty mostly small-scale mixed vegetable producers were identified as potential sites in an area from Yuba City to Stockton. Approximately 30 sites from the southern part of the region were eliminated because of highly variable soil types and the considerable distances involved, leaving a pool of about 30 sites from which the 18 sites sampled by members of at least some of the disciplines were chosen (Table 6-1). The sites selected in 1989 represent a majority of the available organic within a 50-mile radius of the University of California at Davis campus, with 9 of a possible 13 organic or transitional sites being sampled. A much greater number of potential large-scale sites existed relative to the number of other types of sites. Therefore, the large-scale sites chosen were selected on the basis of proximity to organic or transitional sites and from discussions with local farm advisers to ensure that they were representative of farms in the region. Some of the more southern sites rejected in 1989 will be included in 1990, however, to increase the representation of large green-gas tomato producers, for reasons discussed below.

There was reasonable success in ensuring that the location of sites in each of the broad management categories overlapped (Figure 6-2) and that similar ranges of soil types, climatic conditions, surrounding vegetation, and field sizes were represented. In this way the potential for these variables to obscure the effects of different management systems was minimized. Other variables such as planting date, sampling date, and cultivar were not adequately controlled and therefore must be accounted for in all analyses (see below). For example, the abundance of green peach aphids early in the season was highly correlated with the transplant date (r = −0.76, p = 0.0063) rather than management. In contrast, the abundance of other insects (thrips, flea beetles, stink bugs, and various beneficial insects) showed no such relationship.

The six organic and three transitional farms sampled typically produced a diverse mix of both winter and summer vegetables and tree crops, with acreages in tomatoes ranging from less than 1 to 5 acres and total farm size ranging from 10 to 160 acres, except for one transitional farm of 800 acres. Conventional mixed fruit and vegetable producers also grew a mix of vegetables and tree crops on acreages ranging from 1 to 1,500 acres (typically, 200 to 300 acres). In general, 10 to 90 percent of this land was in mixed vegetables (1 to 200 acres), and 1 to 10 acres of the total acreage was in

Suggested Citation:"PART TWO: RESEARCH AND EDUCATION IN THE WESTERN REGION." National Research Council. 1991. Sustainable Agriculture Research and Education in the Field: A Proceedings. Washington, DC: The National Academies Press. doi: 10.17226/1854.
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FIGURE 6-1 Diagram illustrating the general relationships between the types of tomato production systems found in California's Central Valley. Type A refers to small-scale organic mixed vegetable producers, type B refers to the smaller conventional mixed vegetable producers, and type C refers to the large-scale processing or fresh market producers (typically, green-gas [see text]). Type B shares characteristics in common with both the small-scale organic growers (type A) and the large-scale conventional growers (type C). At present, some type C growers are in the process of converting part of their land into organic tomato production.

tomatoes. Six of the conventional farming sites sampled in 1989 fellinto the category of mixed vegetable producers; the remaining three consisted of one large green-gas tomato field and two processing tomato fields into which fresh market tomatoes were transplanted. Although there are some management differences between fresh market and processing tomatoes, there are many important similarities in terms of fertilizer practices, reliance on chemical pest control, large scale of production (typically 40 to 60 acres per tomato field), use of heavy machinery, and, typically, the presence of more severe soil structural and plant disease problems than those in small-scale systems. For these reasons and the fact that large areas of the

Suggested Citation:"PART TWO: RESEARCH AND EDUCATION IN THE WESTERN REGION." National Research Council. 1991. Sustainable Agriculture Research and Education in the Field: A Proceedings. Washington, DC: The National Academies Press. doi: 10.17226/1854.
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FIGURE 6-2 Map showing the locations of (▴) organic/transitional and (◦) conventional sites for the project in 1989.

Central Valley are in these production systems, it was decided that it would be important to include more of the large-scale sites in this study in 1990, even though no long-term organic counterparts in this size category currently exist.

Suggested Citation:"PART TWO: RESEARCH AND EDUCATION IN THE WESTERN REGION." National Research Council. 1991. Sustainable Agriculture Research and Education in the Field: A Proceedings. Washington, DC: The National Academies Press. doi: 10.17226/1854.
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Management Practices

Forms and quantities of nitrogen input varied considerably among the farms studied, ranging from virtually zero (residue of preceding dry bean crop) to various combinations of legume cover crops, compost, manure, earthworm castings, or recommended rates of chemical fertilizer. Insect pest management ranged from zero intervention to extensive use of organic controls (sulfur, Bacillus thuringiensis) or broad-spectrum synthetic insecticides. All farms used some combination of mechanical cultivation and hand hoeing for weed control; in addition, pre- and postemergence herbicides were typically applied on the conventional farms. Irrigation practices also differed between the organic and conventional farms, with about half the organic farmers using drip irrigation for their tomatoes, whereas the majority of conventional farmers used furrow irrigation.

Preliminary Results

Significant differences were observed between management categories based on soil, plant, and disease parameters. However, cultivar and planting and sampling date effects were also significant and were partially confounded with management types. The cultivar effect was mainly due to the fact that one field planted with a tomato cultivar differed substantially from the two more similar cultivars that were planted in all of the other fields. Based on these results, only one cultivar will be studied in the future. When necessary, transplants will be provided to the cooperating growers if they would not usually plant the cultivar selected by the project team. Differences in planting dates are unavoidable. However, confounding by transplant and sampling dates will be minimized in the future by equally dividing earlier and later planting dates over the farm types as much as possible.

Preliminary examination of the data suggests that differences exist between organic and conventional farms with regard to nitrogen mineralization potential, inorganic nitrogen pools, microbial activity, corky root severity, and insect damage. Yield differences were not evaluated in 1989 because of the confounding effects of cultivar and planting date. Average soil nitrate concentrations were higher in conventionally managed soils than in organically managed soils, whereas nitrogen mineralization potential was generally lowest in the conventional soils. Transitional soils tended to be intermediate in both respects. Microbial activity and organic carbon levels followed the same trend as nitrogen mineralization, but differences between organic and conventional farms in terms of organic carbon were less pronounced. In contrast, soil wet aggregate stability (an indication of soil porosity) appears to show no clear trends at this stage. The multivariate analyses will provide a clearer picture of the relationships among the soil variables and what differences exist among management types.

Suggested Citation:"PART TWO: RESEARCH AND EDUCATION IN THE WESTERN REGION." National Research Council. 1991. Sustainable Agriculture Research and Education in the Field: A Proceedings. Washington, DC: The National Academies Press. doi: 10.17226/1854.
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The leaf-baiting technique that was used to determine population levels of Phytophthora parasitica in soil detected the pathogen in both conventional and transitional farms but not in organic farms. However, during the tomato growing season, no phytophthora root rot symptoms were observed on any of the plants sampled, even on farms where Phytophthora propagules were detected in the soil. This discrepancy was probably due to the patchy distribution of the pathogen; disease symptoms were observed in some conventional and transitional fields outside of the sampling area. Corky root caused by Pyrenochaeta lycopersici was observed in all farms at low levels, but disease levels were generally higher in conventional than in organic farms. At this stage, given the low incidence of either disease studied, it is premature to draw conclusions regarding any relationship between soil parameters, such as microbial activity and nitrogen availability, and disease severity observed in the field. In the future, plants from 3 feet of the row will be sampled from each randomly selected location to increase the chance of disease detection. In addition, samples will be collected outside the designated sampling locations to target areas with visible foliar symptoms of phytophthora root rot and to aid in the determination of relationships between disease severity and soil properties.

Initial analyses of field-level data suggest that pairing of organic and transitional sites with conventional sites based on geographic proximity did not add robustness to comparisons of farm-level data on arthropod community abundance. Indeed, it is not clear which of many factors should be used as a basis for pairing sites for this kind of comparison or whether the categories of organic, transitional, and conventional farming themselves are useful in this context. In 1989, many conventional growers actually used insect pest control strategies similar to those of organic growers. Injury levels on tomato foliage tended to be approximately five times greater in organic than in either conventional or transitional fields. The levels of damage observed, however, were low and unlikely to cause significant yield loss, even on the organic farms. The cultural practice of early transplant dates usually results in low damage to fruit by insect pests. In future seasons, data will be obtained from more late plantings for comparisons among management practices and between years. An increase in sample size to 18 fields and more uniform representation of management categories will strengthen the ability to identify field-level trends in damage and abundance of pests and natural enemies.

CONCLUSION

The results available to date show that the approaches taken in this study have proved to be effective. There are clear indications that interesting differences exist between the organic and conventional production systems.

Suggested Citation:"PART TWO: RESEARCH AND EDUCATION IN THE WESTERN REGION." National Research Council. 1991. Sustainable Agriculture Research and Education in the Field: A Proceedings. Washington, DC: The National Academies Press. doi: 10.17226/1854.
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Completion of the multivariate analyses will provide more extensive information than is presently available on interactions between many of the parameters that were measured. At the same time, the study was able to identify critical factors that need to be dealt with more effectively in the future, notably, planting date and cultivar. In light of these results, procedures for subsequent field seasons are being modified to provide greater uniformity. Transplants of the same tomato variety are being provided to all growers, and greater attention is being paid to ensuring that a similar range of planting dates exists among sites representing each management category. An increase in the number of sample units would clearly be beneficial for many aspects of the study. Furthermore, it became obvious that the advantages of having complete data sets for all sites far out-weighed the disadvantage of sampling some sites that may not be ideal for addressing a particular question. In the future it is intended that complete information be collected for at least 18 sites, with essentially even representation of farms covering the spectrum, from large-scale conventional through smaller-scale conventional, transitional, and organic tomato producers.

This multiyear integrated interdisciplinary study of existing farms in one of the world's premier vegetable-producing regions promises to provide valuable insights into the effects of a variety of alternative and conventional management practices on the processes that function within this agroeco-system. While the results pertain most directly to central California agriculture, much of the data should also be relevant to similar irrigated production systems in semiarid irrigated regions of the world. Furthermore, the methods used to achieve an integrated interdisciplinary project with the meaningful involvement of farmers represent a powerful methodological approach for farming systems comparison research.

ACKNOWLEDGMENTS

The authors acknowlege the assistance of R. O'Malley, S. van Nouhuys, V. Morrone, J. P. Mitchell, D. Haaf, and A. Wong for field sampling and technical assistance; P. Johnson for statistical consultations; and R. L. Bugg for stimulating discussions and for providing information on other farming systems studies. In particular, the authors acknowledge their debt to all the growers who have participated in this study and who provided feedback and ideas in addition to their valuable time. The authors are grateful to the LISA program of USDA for funding this research, and D. K. Letourneau also acknowledges receipt of an Academic Senate Faculty Grant from the University of California, Santa Cruz.

Suggested Citation:"PART TWO: RESEARCH AND EDUCATION IN THE WESTERN REGION." National Research Council. 1991. Sustainable Agriculture Research and Education in the Field: A Proceedings. Washington, DC: The National Academies Press. doi: 10.17226/1854.
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Suggested Citation:"PART TWO: RESEARCH AND EDUCATION IN THE WESTERN REGION." National Research Council. 1991. Sustainable Agriculture Research and Education in the Field: A Proceedings. Washington, DC: The National Academies Press. doi: 10.17226/1854.
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7

STEEP: A Model for Conservation and Environmental Research and Education

Robert I. Papendick

The Pacific Northwest wheatlands are plagued with an erosion problem that has become recognized as among the most serious in the United States. Each year, erosion costs the region millions of tons of topsoil that are washed from its croplands. In some places where conventional farming practices are used, as much as 12 bushels of topsoil are eroded for each bushel of wheat produced. Environmental damage to land and water and loss of soil productivity have occurred despite conservation efforts by concerned farmers and government programs that have been implemented for erosion control. One major limitation of these efforts was that research and practice for erosion control were not always coordinated with research and practice for crop production. For the most part, each one was dealt with as a separate issue. As a result, control practices often increased the cost of crop production and thus were not acceptable to farmers.

More people are becoming sensitive to the serious consequences of soil erosion and its threat to the environment and the economic security of the region. In the future, the capability of maintaining high yields in the inherently fertile soils of the Northwest will depend largely on the ability to prevent the loss of topsoil and the depletion of soil organic matter.

Erosion is the result of a combination of factors, including (1) a winter precipitation climate with high amounts of frozen soil runoff, (2) the exceptionally steep, irregular topography, and (3) management and cropping systems that leave the soil bare as the winter rainy season approaches. Management is especially a problem when wheat and barley are seeded in the fall and when fall moldboard plowing is done in preparation for the following spring planting. Average annual erosion rates in the Palouse

Suggested Citation:"PART TWO: RESEARCH AND EDUCATION IN THE WESTERN REGION." National Research Council. 1991. Sustainable Agriculture Research and Education in the Field: A Proceedings. Washington, DC: The National Academies Press. doi: 10.17226/1854.
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region of eastern Washington State range from 17 to 25 tons/acre (approximately 1/8 inch of topsoil) with conventional tillage practices. Each year approximately one-third of the eroded soil is washed into streams, rivers, lakes, and harbors. The sediment in water and the buildup of silt reduces irrigation efficiency and hydroelectric power generation. It also adversely affects many desirable ecosystems and the use of water for industrial and recreational purposes. Costs to remove silt from roadsides and ditches alone amount to several millions of dollars each year in the three-state region of Washington, Oregon, and Idaho.

THE STEEP PROGRAM

STEEP (solutions to environmental and economic problems) is a multidisciplinary research and education program in the three Pacific Northwest states designed to focus scientific and extension efforts on the control of soil erosion on croplands (Miller and Oldenstadt, 1987; Oldenstadt et al., 1982). The central idea is that soil erosion and water pollution can be reduced significantly by integrating new and improved soil and crop management practices, plant types, pest control methods, and socioeconomic principles into farming systems to achieve sustainable crop production. The research approach is to reduce environmental damage while simultaneously maintaining or increasing agricultural productivity, which is important to the economic and social welfare of the region and the nation.

The motivation for this research approach came from wheat producer organizations in the region. They organized the initial discussions on the subject, obtained supplemental congressional funding for research support, and continue to support and monitor its progress. Funds for STEEP program research have been made available each year since 1976 by a special grant from the U.S. Department of Agriculture (USDA) to the Agricultural Experiment Stations in Washington, Oregon, and Idaho and by appropriations to the Agricultural Research Service (ARS) of USDA.

The STEEP program effort has worked to develop and use new and improved systems of conservation management in which tillage methods, crop rotations, plant types, and methods of plant protection are integrated into complete management systems that minimize erosion without adversely affecting costs or levels of production. There are two main research approaches for erosion control: (1) development of conservation cropping systems along with plant types that can produce economical yields in trashy, hard-soil seedbeds, and (2) development of planting methods for winter wheat and barley in the early fall to provide increased ground cover before winter. Also included is research on the erosion and runoff process and the prediction of erosion and runoff with emphasis on frozen and thawing soils. Emphasis is given to the control of diseases, weeds, insects,

Suggested Citation:"PART TWO: RESEARCH AND EDUCATION IN THE WESTERN REGION." National Research Council. 1991. Sustainable Agriculture Research and Education in the Field: A Proceedings. Washington, DC: The National Academies Press. doi: 10.17226/1854.
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and rodents and to socioeconomic factors in the development of conservation tillage systems.

The development and tailoring of new conservation systems for the region has involved ARS of USDA and university scientists from as many as 10 disciplines. These scientists constantly interact to develop consistent sets of data for practices that are compatible with conservation management systems in the Pacific Northwest. The work has an impact on 10 million acres of cropland in the Columbia Plateau and Palouse-Nez Perce Prairies, Columbia Basin, Snake River Plains, and Willamette-Puget Sound Valleys in Washington, Oregon, and Idaho.

STEEP Program Objectives

The overall research effort of the STEEP program is organized into six major objectives (Oldenstadt et al., 1982). Under each objective there are several subobjectives (not listed here), each of which covers a specific research topic that is to be integrated into the conservation management system being developed. The main emphasis of each major objective is given and discussed below.

  1. Tillage and plant management. Develop combinations of tillage, cropping, residue management, and weed control systems to control erosion and increase crop production.

  2. Plant design. Develop crop cultivars with morphological and rooting characteristics that reduce erosion and maintain food (feed) production when grown in conservation cropping systems.

  3. Erosion and runoff prediction. Improve the understanding and prediction of erosion and runoff processes as they are affected by climate, topography, soils, tillage, and crop management for use as a decision-making tool for planning conservation applications.

  4. Pest management. Integrate control of weeds, diseases, rodents, and insects into conservation tillage and plant management systems.

  5. Socioeconomics of erosion control. Determine the impact of improved erosion control practices on farm organizations, cost, and net incomes and on maintaining agricultural productivity in the region.

  6. Soil erosion-productivity relationships. Develop relationships that show how erosion affects crop production over both the short and long term.

All of the objectives have a common goal, that is, the development of farming systems for control of soil erosion. Each objective contributes in a special way to the achievement of this goal and is a necessary link in the integration approach. The objectives and/or subobjectives are revised as necessary as new problems arise in the process of changing tillage and cropping systems.

Suggested Citation:"PART TWO: RESEARCH AND EDUCATION IN THE WESTERN REGION." National Research Council. 1991. Sustainable Agriculture Research and Education in the Field: A Proceedings. Washington, DC: The National Academies Press. doi: 10.17226/1854.
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ORGANIZATION AND MANAGEMENT OF THE RESEARCH PROGRAM

Members of the research team, numbering some 30 to 40 scientists, have repeatedly demonstrated their ability to work together over the past 14 years. Every effort is made to ensure that the solutions developed are practical and workable. The size of the effort needed to solve the soil erosion problem is greater than the resources of any single research institution or agency in the region. The combined effort, which is bound together by the common objectives, coordination of effort, and supplemental funding, is demonstrating a high degree of success.

A coordinating committee comprising six scientists, one extension specialist, and a representative from the USDA Soil Conservation Service has the responsibility for organizing annual reporting sessions. These sessions serve as a mechanism for monitoring progress for the wheat industry and interested federal and state agencies, and for facilitating interactions among the participating scientists. Scientists are encouraged to submit research proposals in their area of interest within the six objectives. These are passed through departmental channels, and the research administrators may call on the coordinating committee to review and prioritize the individual proposals and provide recommendations for funding. Research grants are usually made for a 3-year period, after which they are terminated or extensively revised. This turnover provides an opportunity for more scientists to participate in the program and also provides a means to maintain a balance in the needed disciplines.

STEEP Program Extension

An extension component was added to the STEEP program in 1982 to help disseminate new research findings and to assist farmers in applying research results in the field. One specialist is located at the Columbia Plateau Conservation Research Center at Pendleton, Oregon, and the other is located on the University of Idaho campus at Moscow, Idaho. These specialists interact on a regular basis with scientists in their areas and host radio and television programs, write newsletters, organize grower information meetings, and conduct tours of fields. The STEEP program extension component is a vital link in narrowing the gap between the generation of research information and farm applications.

Farmer Support

The STEEP program has often been labeled as a “growers' program,” meaning that individual farmers and the wheat grower organizations have

Suggested Citation:"PART TWO: RESEARCH AND EDUCATION IN THE WESTERN REGION." National Research Council. 1991. Sustainable Agriculture Research and Education in the Field: A Proceedings. Washington, DC: The National Academies Press. doi: 10.17226/1854.
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provided major inputs into the development and operation of the research and extension program. Not only do the growers seek support for STEEP program funding, they also assist in establishing research priorities and stimulating the needed research in other ways. Growers actively participate in the annual reviews, aid the coordinating committee in the evaluation of existing research projects, and suggest new problem areas and needs for future research based on their own experiences. Much of the guidance on the direction of research has come from the farmers themselves. The growers were largely responsible for the addition of the extension component to the STEEP program.

The wheat grower organizations of the three Pacific Northwest states have done much to obtain the special grants funding that supports the research. By pooling their resources, they have been able to convince the U.S. Congress of the seriousness of the erosion problem and the need for increased research on erosion control. Their efforts have largely been responsible for marshaling the resources of the various research agencies and of agri-industry into this high-priority research area.

STEEP PROGRAM RESEARCH ACCOMPLISHMENTS

The STEEP progam has contributed a number of major scientific and technical advancements in conservation farming since its inception. The following are a few examples of accomplishments for each of the six main objectives.

Tillage and Plant Management
  • The yield advantages and improved efficiency of band placement of nitrogen fertilizer in no-till planting of small grains were established (Koehler et al., 1987).

  • No-till drills that have the capability to band fertilizer and sow small grains in moderate to heavy amounts of crop residues and in hard, dry soils have been developed (Hyde et al., 1987).

  • A crop residue decomposition model that uses generated residue and soil temperature-moisture inputs was developed for predicting the rate at which surface residues disappear in the field (Stroo et al., 1989).

  • A wheat growth model that predicts tillage and residue effects on developmental stages of wheat growth was developed (Klepper et al., 1987).

Plant Design
  • Wheat cultivars that perform best in conventional tillage management systems are the ones that perform best in conservation tillage systems (Allan and Peterson, 1987).

Suggested Citation:"PART TWO: RESEARCH AND EDUCATION IN THE WESTERN REGION." National Research Council. 1991. Sustainable Agriculture Research and Education in the Field: A Proceedings. Washington, DC: The National Academies Press. doi: 10.17226/1854.
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  • Risks associated with seeding in the early fall to provide good ground cover over the winter have been reduced by developing wheat types that have increased resistance to rusts, foot and root rots, flag smut, and snow mold (Allan and Peterson, 1987).

  • Spring wheats that produce only primary tillers were found to be more desirable than multiple tiller-producing varieties in areas with low amounts of rainfall. In these areas, more spring cropping instead of use of summer fallow is encouraged to control erosion (Konzak et al., 1987).

Erosion and Runoff Prediction
  • New factor relationships were developed for the Universal Soil Loss Equation to improve soil erosion prediction for the Pacific Northwest. These relationships are now being used by the Soil Conservation Service in farm planning applications to meet conservation compliance established in the Food Security Act of 1985 (McCool et al., 1987).

  • A new method was developed for computing erosivity (R factor) values for rainfall characteristics using hourly rainfall data that are generally more available than the otherwise required 15-minute break-point rainfall data (Istok et al., 1987).

  • A rill meter was developed for measurement of erosion in the field. This tool formed the basis of the new data collection needed to develop Universal Soil Loss Equation, length-of-slope (LS) factor relationships for the Pacific Northwest (McCool et al., 1981).

Pest Management
  • Conservation tillage practices and intensive cropping of small grains was found to increase root diseases of wheat and barley (Wiese et al., 1987).

  • Studies determined that root diseases of wheat or barley in a conservation tillage system can be controlled by using a 3-year crop rotation, with the cereal being grown only 1 year in 3 (see R. J. Cook, “Challenges and Rewards of Sustainable Agriculture Research and Education ,” this volume).

  • Improved methods of herbicide management were developed for control of annual grasses and broadleaf weeds in no-till wheat, barley, and chemical fallow (Rydrych, 1987; Thill et al., 1987).

Socioeconomics of Erosion Control
  • The diffusion of conservation practices in the Northwest will take considerable time and will depend to a large extent on changes in the context, the innovation, and the characteristics of potential adapters (Dillman et al., 1987).

Suggested Citation:"PART TWO: RESEARCH AND EDUCATION IN THE WESTERN REGION." National Research Council. 1991. Sustainable Agriculture Research and Education in the Field: A Proceedings. Washington, DC: The National Academies Press. doi: 10.17226/1854.
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  • STEEP program research provided valuable insights for the highly erodible land protection provisions in the Food Security Act of 1985 (Hoag and Young, 1985).

  • Studies that have surveyed farmers on their adoption of erosion control practices showed that (1) absentee landowners are not a major constraint to erosion control; (2) the major constraints to erosion control appear to be factors external to the farmer himself, especially the rules imbedded in government programs; and (3) over the past 10 years there has been a positive change in farmer attitudes toward erosion control as well as implementation of erosion control practices (Carlson et al., 1987; Dillman and Carlson, 1982).

Soil Erosion-Productivity Relationships
  • Wheat yield losses resulting from the loss of topsoil have been masked by technological progress, that is, improved varieties, fertilizer management, and weed control (Papendick et al., 1985; Walker and Young, 1986; Young et al., 1985).

  • A computer modeling study supported by field data showed that the effect of erosion on the loss of wheat yields and the anticipated payoff from future technical progress is greater for deep topsoils than it is for shallow topsoils (Young, 1984).

IMPACTS OF STEEP PROGRAM RESEARCH

To what degree have the objectives of the STEEP program been achieved? Has erosion on cropland been controlled? Has farm profitability been maintained or increased?

After 14 years of the STEEP program, erosion still occurs at unacceptable levels on Pacific Northwest croplands, and some farmers are making less money than they did in past years. Nevertheless, the benefits of STEEP program research are becoming evident. There has been a visible increase in the adoption of new soil and crop conservation management technologies developed or refined by STEEP program researchers. Much of the credit for this goes to the STEEP program research on fertilizer placement and the subsequent development of the fertilizer banding (placing fertilizer close to the seeds) capability of the no-till drills that became commercialized in the early 1980s. Conservation methods have enabled farmers to reduce the number of tillage operations on wheat-based rotations from five or more to less than three. These methods leave the seedbed with a rough surface and covered with residues that are effective in controlling erosion.

Much has been learned about the relationships between tillage and plant diseases and how these can be controlled with residue management and

Suggested Citation:"PART TWO: RESEARCH AND EDUCATION IN THE WESTERN REGION." National Research Council. 1991. Sustainable Agriculture Research and Education in the Field: A Proceedings. Washington, DC: The National Academies Press. doi: 10.17226/1854.
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crop rotations. Methods have been devised to move pathogen-infested residues away from the seed row. Crop rotation systems have also been designed to reduce adverse biological effects in no-till systems. Economic studies have shown the long-term benefits of soil conservation and how cost-sharing aids in implementation of the best management practices by defraying the added short-term costs that otherwise could discourage their use by farmers. Overall, the STEEP program, more so than any other program, has created increased public awareness of soil erosion and its consequences and has made growers much more receptive to implementing conservation measures on their farms.

FUTURE DIRECTIONS

Despite the technological advances made by the STEEP program, soil erosion is still a major environmental and economic problem for the Pacific Northwest region. Development of better conservation practices and achievement of more widespread application of such practices on the land remains an urgent, high-priority need. The mandatory conservation compliance requirements of the Food Security Act of 1985 will likely speed up the adoption of no-till and other surface tillage practices, and many growers will be trying these practices on their farms for the first time in the next several years. Many technical problems relating to the use of these conservation practices have not yet been solved, and consequently, their final economic and social acceptability are not known. For example, many farmers will have difficulty planting and harvesting crops and controlling weeds, diseases, and other pests in seedbeds that are rough-tilled or contain high amounts of surface residues. These obstacles can frequently be overcome in research plots; but they cannot always be overcome on farmers' fields for many reasons, including the lack of know-how, inadequate equipment, cost or time limitations, and variations in soil characteristics. Much remains to be done to accomplish the large-scale adoption of conservation tillage technology on the region's farms.

Emerging Issues

In addition to soil erosion, other concerns have now placed land stewardship in a new context. Water quality will be a major national issue of the 1990s. In the future, increasingly severe restrictions on chemical and nutrient management are likely to be mandated legislatively. Fewer agricultural chemicals will be available to farmers, particularly for minor-use crops, because chemical manufacturers face increased registration restrictions and expenses. Other issues that farmers must face include energy conservation,

Suggested Citation:"PART TWO: RESEARCH AND EDUCATION IN THE WESTERN REGION." National Research Council. 1991. Sustainable Agriculture Research and Education in the Field: A Proceedings. Washington, DC: The National Academies Press. doi: 10.17226/1854.
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environmental stability, fish and wildlife protection, farm worker health, food safety, and maintenance of net farm income. Conservation farming for erosion control affects all of these issues and concerns. For example, it appears that with current technology, conservation practices such as reduced tillage and no-till farming will usually require increased use of pesticides and nitrogen fertilizers. Because of the reduced runoff and evaporation under conservation tillage practices, this may increase infiltration and leaching of chemicals into groundwater. If this is true, the chemical-intensive practices being developed today likely will not be acceptable in the future. The same is true for the potential adverse impacts of chemicals on wildlife, farm worker health, and food safety. Thus, concerns for efficient crop production; conservation of soil, water, and energy; and maintaining net farm income must be integrated with the need to safeguard human health and protect the environment.

About 2 million acres of highly erodible land in the three Pacific Northwest states are now in the Conservation Reserve Program (CRP). This land is under 10-year contracts so that only grasses are grown or the land is used for other activities that do not require tillage. Much of this land had been seriously degraded because of excessive erosion rates as a result of previously used cropping systems. If these lands are converted back to crops after the expiration of CRP contracts, the challenge will be to conserve the accrued productivity benefits from 10 years of growing grasses by returning to cropping systems that are more sustainable. The outcome of this post-CRP transition will have a profound impact on soil erosion, water quality, farm income, and the future of agriculture in the region.

STEEP II Program

The STEEP program has achieved an organizational structure and stance that makes the program ideally poised to meet the production, conservation, and environmental challenges of the 1990s. It has a proven ability to mobilize scientific and extension resources on relatively short notice to solve regional problems. A proposal has been drafted for a replacement project for the expiring STEEP program, known as the STEEP II program. This revised program will build on the progress and accomplishments of the STEEP program. STEEP II will seek to coordinate a regional research and information delivery system designed to provide growers in the Pacific Northwest with advanced technologies for simultaneously controlling soil erosion and protecting water quality while achieving more cost-efficient crop production and increased farm profitability.

It is proposed that the STEEP II program should be expanded to include water quality protection in addition to erosion control. The program will be organized around three main objectives:

Suggested Citation:"PART TWO: RESEARCH AND EDUCATION IN THE WESTERN REGION." National Research Council. 1991. Sustainable Agriculture Research and Education in the Field: A Proceedings. Washington, DC: The National Academies Press. doi: 10.17226/1854.
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  1. Obtain and integrate new technical and scientific information on soils, crop plants, pests, energy, and farm profitability into sustainable, whole-farm management systems.

  2. Develop tools for assessing the impacts of farming practices on erosion and water quality.

  3. Develop and implement programs for dissemination of information and transfer of technology to the farm.

Within these objectives, considerable effort will be given to developing conservation cropping systems that will consistently produce acceptable crop yields, are adaptable to farmers in the different agronomic zones, and are environmentally safe. Attention will be directed toward overcoming factors that now limit crop growth with conservation planting. Some of the factors that have been identified include increased root diseases and weed infestations associated with increased surface residues, and increased pests in wheat planted early in the fall to enhance ground cover for erosion control in the winter and spring. Other limiting factors related to nutrient cycling and the physical properties of soil will also be examined.

Soil microbial properties of various tillage and cropping systems will be assessed to develop methods and principles that will prevent plant diseases, reduce the potential for nutrient leaching, and increase the use efficiency of applied fertilizers and organic amendments. Increased attention will also be given to new tillage methods that can complement the use of surface residues for erosion control. Research will be conducted to explore management strategies and options for farmers on how to maximize the benefits of soil productivity of CRP lands while in grass and how to return these highly erodible lands from grass to more sustainable cropping systems.

Development and testing of erosion and water quality control systems will include evaluations of economic impacts at the farm and regional levels and of social factors that limit or enhance the adoption of conservation practices by farmers. The STEEP II program will also give new emphasis to developing methodologies for on-farm research and providing scientific backup to research and education projects such as those supported by the USDA low-input sustainable agriculture (LISA) program that involve direct work with growers in testing treatments on large plots or whole fields.

Erosion and water quality models will be developed as tools to evaluate the impacts of conservation tillage and other management options on runoff and erosion, water conservation, and water quality. Physical and chemical process models will ultimately be incorporated with crop production models to provide an interactive link between crop production practices, erosion rates, nutrient use efficiency, and the potential for nutrient escape from the crop root zone.

Suggested Citation:"PART TWO: RESEARCH AND EDUCATION IN THE WESTERN REGION." National Research Council. 1991. Sustainable Agriculture Research and Education in the Field: A Proceedings. Washington, DC: The National Academies Press. doi: 10.17226/1854.
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A variety of innovative approaches will be used for information transfer in the STEEP II program. These include on-farm research and demonstration projects and associated field tours, decision-aid computer software, newsletters, farm magazine and newspaper articles, cooperative extension publications, meeting presentations, conferences and workshops, and audiovisual aids.

CONCLUSION

The momentum for conservation is present and appears to be accelerating. The STEEP program continues to be the best vehicle for coordinating the research and extension efforts needed to ensure that national and regional goals for resource protection and economic viability are achieved.

REFERENCES

Allan, R. E., and C. J. Peterson, Jr. 1987. Winter wheat plant design to facilitate control of soil erosion. Pp. 225–245 in STEEP—Conservation Concepts and Accomplishments, L. F. Elliott, ed. Pullman, Wash.: Washington State University Press.

Carlson, J. E., D. A. Dillman, and L. Boersma. 1987. Attitudes and behavior about soil conservation in the Pacific Northwest. Pp. 333–341 in STEEP—Conservation Concepts and Accomplishments, L. F. Elliott, ed. Pullman, Wash.: Washington State University Press.

Dillman, D. A., D. M. Beck, and J. E. Carlson. 1987. Factors affecting the diffusion of no-till agriculture in the Pacific Northwest. Pp. 343–364 in STEEP—Conservation Concepts and Accomplishments, L. F. Elliott, ed. Pullman, Wash.: Washington State University Press.

Dillman, D. A., and J. E. Carlson. 1982. Influence of absentee landlords on soil erosion control practices. Journal of Soil and Water Conservation 37:37–40.

Hoag, D., and D. Young. 1985. Toward effective land retirement legislation. Journal of Soil and Water Conservation 40:462–465.

Hyde, G., D. Wilkins, K. Saxton, J. Hammel, G. Swanson, R. Hermanson, E. Dowding, J. Simpson, and C. Peterson. 1987. Reduced tillage seeding equipment. Pp. 41–56 in STEEP—Conservation Concepts and Accomplishments, L. F. Elliott, ed. Pullman, Wash.: Washington State University Press.

Istok, J. D., J. F. Zuzel, L. Boersma, D. K. McCool, and M. Molnau. 1987. Advances in our ability to predict rates of runoff and erosion using historical climatic data. Pp. 205–222 in STEEP—Conservation Concepts and Accomplishments, L. F. Elliott, ed. Pullman, Wash.: Washington State University Press.

Klepper, B. L., R. W. Rickman, and P. M. Chevalier. 1987. Wheat plant growth in conservation tillage. Pp. 93–107 in STEEP—Conservation Concepts and Accomplishments, L. F. Elliott, ed. Pullman, Wash.: Washington State University Press.

Koehler, F. E., V. L. Cochran, and P. E. Rasmussen. 1987. Fertilizer placement, nutrient flow, and crop response in conservation tillage. Pp. 57–65 in STEEP—Conservation Concepts and Accomplishments, L. F. Elliott, ed. Pullman, Wash.: Washington State University Press.

Suggested Citation:"PART TWO: RESEARCH AND EDUCATION IN THE WESTERN REGION." National Research Council. 1991. Sustainable Agriculture Research and Education in the Field: A Proceedings. Washington, DC: The National Academies Press. doi: 10.17226/1854.
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Konzak, C. F., D. W. Sunderman, E. A. Polle, and W. L. McCuiston. 1987. Spring wheat plant design for conservation tillage management systems. Pp. 247–273 in STEEP—Conservation Concepts and Accomplishments, L. F. Elliott, ed. Pullman, Wash.: Washington State University Press.

McCool, D. K., M. G. Dossett, and S. J. Yecha. 1981. A portable rill meter for field measurement of soil loss. Erosion and sediment transport measurement. Proceedings of the Florence Symposium, June 1981. IAHS Publication No. 133. Wallingford, England: International Association of Hydrological Sciences.

McCool, D. K., J. F. Zuzel, J. D. Istok, G. E. Formanek, M. Molnau, K. E. Saxton, and L. F. Elliott. 1987. Erosion processes and prediction for the Pacific Northwest. Pp. 187–204 in STEEP—Conservation Concepts and Accomplishments, L. F. Elliott, ed. Pullman, Wash.: Washington State University Press.

Miller, R. J., and D. Oldenstadt. 1987. STEEP history and objectives. Pp. 1–7 in STEEP—Conservation Concepts and Accomplishments, L. F. Elliott, ed. Pullman, Wash.: Washington State University Press.

Oldenstadt, D. L., R. E. Allan, G. W. Bruehl, D. A. Dillman, E. L. Michalson, R. I. Papendick, and D. J. Rydrych. 1982. Solutions to Environmental and Economic Problems (STEEP). Science 217:904–909.

Papendick, R. I., D. L. Young, D. K. McCool, and H. A. Krauss. 1985. Regional effects of soil erosion on crop productivity—the Palouse area of the Pacific Northwest. Pp. 305–320 in Soil Erosion and Crop Productivity, R. F. Follett and B. A. Stewart, eds. Madison, Wis.: American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America.

Rydrych, D. J. 1987. Weed management in wheat-fallow conservation tillage systems. Pp. 289–298 in STEEP—Conservation Concepts and Accomplishments, L. F. Elliott, ed. Pullman, Wash.: Washington State University Press.

Stroo, H. F., K. L. Bristow, L. F. Elliott, R. I. Papendick, and G. S. Campbell. 1989. Predicting rates of wheat residue decomposition. Soil Science Society of America Journal 53:91–99.

Thill, D. C., V. L. Cochran, F. L. Young, and A. G. Ogg, Jr. 1987. Weed management in annual cropping limited-tillage systems. Pp. 275–287 in STEEP—Conservation Concepts and Accomplishments, L. F. Elliott, ed. Pullman, Wash.: Washington State University Press.

Walker, D. J., and D. L. Young. 1986. Effect of technical progress on erosion damage and economic incentives for soil conservation. Land Economics 62:89–93.

Wiese, M. V., R. J. Cook, D. M. Weller, and T. D. Murray. 1987. Life cycles and incidence of soilborne plant pathogens in conservation tillage systems. Pp. 299–313 in STEEP—Conservation Concepts and Accomplishments, L. F. Elliott, ed. Pullman, Wash.: Washington State University Press.

Young, D. L. 1984. Modeling agricultural productivity impacts of soil erosion and future technology. Pp. 60–85 in Future Agricultural Technology and Resource Conservation, B. C. English, J. A. Maetzold, B. R. Holding, and E. O. Heady, eds. Ames, Iowa: Iowa State University Press.

Young, D. L., D. B. Taylor, and R. I. Papendick. 1985. Separating erosion and technology impacts on winter wheat yields in the Palouse: A statistical approach. Pp. 130–142 in Erosion and Soil Productivity, D. K. McCool, ed. ASAE Publication No. 8-85. St. Joseph, Mich.: American Society of Agricultural Engineers.

Suggested Citation:"PART TWO: RESEARCH AND EDUCATION IN THE WESTERN REGION." National Research Council. 1991. Sustainable Agriculture Research and Education in the Field: A Proceedings. Washington, DC: The National Academies Press. doi: 10.17226/1854.
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8

Soil Moisture Monitoring: A Practical Route to Irrigation Efficiency and Farm Resource Conservation

Gail Richardson

Surface water and groundwater withdrawals for farm irrigation in the 17 western states constitute about 85 percent of the region' s developed supplies. More efficient irrigation management could reduce aquifer depletion, protect water quality by curtailing runoff and drainage, help to control salinization and soil erosion, and make more water available for other uses. The potential for improvement is vast, but the required changes must occur field by field and farmer by farmer. There are no shortcuts.

In the past few years, because of research by INFORM (a nonprofit environmental research organization), training programs by the Soil Conservation Service (SCS) of the U.S. Department of Agriculture and support from private foundations, the California Energy Commission, and the Western Area Power Administration (WAPA), farmers in California and Colorado have adopted a low-cost, site-specific water management method on more than 70,000 irrigated acres. They use the information to reduce their water and energy use.

Corn and wheat farmers in Colorado are the largest and fastest-growing pool of users. Most of them irrigate with center-pivot sprinklers. Ranchers, field crop farmers, and specialty crop growers in California are also adopting the method and showing its applicability to diverse crops, soils, and farm operations—and especially to surface irrigation systems like those that predominate in irrigated agriculture systems in the United States.

Farmer testimony and field evidence now amply justify broader public support for soil moisture monitoring as a component of integrated conservation plans for irrigated farms. There is also growing evidence that soil moisture monitoring is effective in persuading farmers of dryland as well

Suggested Citation:"PART TWO: RESEARCH AND EDUCATION IN THE WESTERN REGION." National Research Council. 1991. Sustainable Agriculture Research and Education in the Field: A Proceedings. Washington, DC: The National Academies Press. doi: 10.17226/1854.
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as irrigated crops in water-short regions (where wind erosion problems are concentrated) to convert to various forms of conservation tillage. Moisture monitoring is currently in use on 10,000 acres of dryland wheat in Colorado and is spreading.

HOW SOIL MOISTURE MONITORING REDUCES GUESSWORK AND IMPROVES FARM RESOURCE MANAGEMENT

“Surface moisture, like beauty, is thin.” These words of a Colorado farmer capture a common predicament. The field surface masks what lies beneath it. Irrigators must, therefore, guess about the effects of rainfall, snow, irrigation, sun, wind, and cultivation practices on moisture levels in the root zone. They follow instinct, the calendar, or their neighbors; and when in doubt, they run water.

Soil moisture monitoring reduces this uncertainty. It gives irrigators a record of the rise and fall in moisture levels at several soil depths in a field. It enables them to see, for example, whether an irrigation fully refills the root zone (often it does not, even if plenty of water is applied) and how long it sustains crop growth before another irrigation is needed.

Each field has unique soils and a unique history. Solutions to over-or underwatering on one field may be inappropriate on another. Site-specific trial-and-error experiments guided by soil moisture data help farmers solve such puzzles. They give farmers the direct proof they need to assess which of various possible remedies to irrigation problems actually increase their efficiency, reduce costs, and maintain or improve yields. Changes they are likely to adopt are described below.

Scheduling Irrigations To Meet Crop Needs

Farmers who monitor moisture changes in the root zone often find that they can delay irrigation in the spring until crops deplete stored rainfall, space irrigations farther apart during the season, and on some crops, cut water off earlier toward the season's end. These changes are often straightforward and can bring sizable water and energy cutbacks and cost reductions.

Managing Equipment More Efficiently

Colorado farmers typically run their center-pivot sprinklers as fast as they will go, often reapplying water on wet field sections before the last dousing has been absorbed. Such practices increase surface runoff and can damage equipment and fields. Soil moisture monitoring has shown that slower rotations result in better moisture penetration, fuller utilization of storage capacity in the root zone, and less runoff. Similarly, monitoring can

Suggested Citation:"PART TWO: RESEARCH AND EDUCATION IN THE WESTERN REGION." National Research Council. 1991. Sustainable Agriculture Research and Education in the Field: A Proceedings. Washington, DC: The National Academies Press. doi: 10.17226/1854.
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help irrigators adjust pipeline valves, select siphons of appropriate size, and adapt all types of sprinkler systems to specific field and soil conditions.

Controlling Distribution and Drainage

Surface irrigators often apply too much water at one field end and not enough at the other, as data collected by INFORM and SCS from California fields amply show. Heavy drainage and the leaching of chemicals can thus occur at the wet end, even though the total application may not exceed the volume needed to meet crop needs. Farmers who detect these problems by soil moisture monitoring are often motivated primarily to correct the underirrigation on the dry field end because of its potential to damage yields. Sometimes a change in the water application rate alone will improve distribution uniformity and reduce drainage.

Reducing Soil Compaction and Infiltration Problems

Compacted soil layers lying beneath a field surface can restrict water infiltration below relatively shallow depths and cramp root growth into narrow soil bands. In addition to depressing yields, compaction is a major contributor to surface runoff. Soil moisture monitoring helps farmers locate these restrictive layers and evaluate the effectiveness of potential remedies. Other chemical or physical conditions that impede soil water movement and often contribute to runoff can be similarly analyzed and remedied by using soil moisture data to evaluate trial-and-error field experiments.

Heavy harvesting equipment creates more compaction on wet ground than it does on dry ground. Soil moisture monitoring helps irrigators improve the timing of irrigation cutoff dates to ensure a dry, less damageable field at the time of harvest. A drier field also reduces wear and tear on equipment.

Converting to Conservation Tillage

Tillage systems that leave plant remains on field surfaces typically increase moisture retention at deep levels in the root zone and control soil erosion. With soil moisture monitoring, farmers on dryland as well as irrigated fields can see these moisture-saving benefits for themselves. This field proof can be a persuasive means of converting them to ridge-till, no-till, and other forms of conservation tillage. Good examples of this can be found in Colorado.

Integrated Resource Management

After several seasons, farmers who use moisture data to manage water, equipment, crops, and soils may be drawn step-by-step into a virtual revolu-

Suggested Citation:"PART TWO: RESEARCH AND EDUCATION IN THE WESTERN REGION." National Research Council. 1991. Sustainable Agriculture Research and Education in the Field: A Proceedings. Washington, DC: The National Academies Press. doi: 10.17226/1854.
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tion in their practices. Since 1987, on Colorado's eastern plains overlying the Ogallala Aquifer, soil moisture monitoring is playing a central role in convincing mainstream grain producers to adopt an integrated conservation package, component by component.

The first component is typically pump tests (by nature of their work, farmers understand motors). Then come soil moisture monitoring, adjustments of irrigation schedules and equipment, the identification and analysis of soil compaction, year-round monitoring of dryland as well as irrigated fields, the substitution of no-till for clean fallow tillage methods, conversion to ridge-till methods on irrigated fields (with major reductions in herbicide use), and conversion to low-energy precision application sprinkler technology. The financial and environmental benefits of these interrelated changes far exceed those achieved through improved irrigation scheduling alone.

TOOLS FOR MONITORING SOIL MOISTURE

The simplest form of soil moisture monitoring involves forcing a metal rod into the ground to see how deep it penetrates. (A dry soil layer will stop it.) Rods with special tips can be used to remove soil samples from various depths to examine their moisture content. These tools are useful for spot-checking wet or damp fields, but they are unusable after a field surface dries out.

For the systematic and continuous monitoring of soil moisture levels at deeper as well as shallower root zone depths, three other field tools are available. These tools are suited to different uses and vary in price.

The neutron probe emits neutrons from radioactive material into soil that has been previously analyzed for its water-holding capacity and prepared for testing. A counter records the neutrons that slow down after colliding with hydrogen atoms in water molecules. This count establishes the soil's water content with great precision. One unit costs about $4,000, and the user must be licensed by the Atomic Energy Commission.

The neutron probe is used primarily by researchers, private consultants, irrigation or water district staff, and farm advisers who are trained to do the tests and interpret the results for farmers. The probe can be used under all field conditions and on all irrigation systems.

Tensiometers are long plastic tubes (typically 2 to 4 feet in length) that are filled with water and equipped with a vacuum gauge. Their ceramic-tip ends are inserted into root zones and, as the root zone dries out, water that is “pulled” from the tubes creates a vacuum that indicates the soil's dryness: the drier the soil the stronger the vacuum. Tensiometers cost about $40 each.

Tensiometers are useful in fields with high moisture conditions, such as those maintained by certain trickle and drip systems. They are less useful for monitoring full wetting and drying cycles, because in heavier soils they

Suggested Citation:"PART TWO: RESEARCH AND EDUCATION IN THE WESTERN REGION." National Research Council. 1991. Sustainable Agriculture Research and Education in the Field: A Proceedings. Washington, DC: The National Academies Press. doi: 10.17226/1854.
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become inoperative below a relatively wet range. Problems of breakage and maintenance make them impractical for use on field crops. They are more commonly used on permanent crops.

Gypsum blocks are small electrical sensors that are implanted in root zones. Wires attached to electrodes inside each one are drawn to the soil surface. By plugging the protruding wires into a hand-held meter, farmers get a reliable relative reading of moisture conditions surrounding the buried block: Conductivity is high under wet soil conditions and low under dry conditions.

Gypsum blocks are used in sets (stations) to monitor three or four soil depths at the same site. About six monitoring sites are required on surface-irrigated fields for analyzing patterns of water distribution, but as few as one or two sites can be sufficient on these or other fields where distribution is known to be relatively uniform.

Gypsum blocks cost from $3.50 to $14.00 each. Meters for reading them run from $150 to $600. Gypsum blocks are adaptable to nearly all crops and soils and all except high-moisture irrigation systems. They normally last 2 to 4 years in well-drained soils.

Soil Moisture Monitoring and Other Approaches to Irrigation Management

For purposes of system evaluation and irrigation scheduling, soil moisture monitoring can often be combined with—and enhanced by—other tools and approaches. These include the use of evapotranspiration data to predict water consumption by crops and plan irrigation schedules, pump tests and other equipment evaluations, and advance-recession analyses of irrigation distribution on surface-irrigated fields that help farmers analyze and correct inefficient practices.

INFORM'S RESEARCH: FORERUNNERS AND FINDINGS

Most of the scientific testing of gypsum blocks was done in the 1940s and 1950s and predates recent improvements in block design. An exception is the work of D. W. Henderson (now retired) of the University of California at Davis, whose decades of laboratory research provided, by the late 1970s, what may be the richest store of technical data ever accumulated. Unfortunately, Henderson published very few of his findings.

Now, after a 10-year hiatus, laboratory testing with gypsum blocks has resumed at the University of California at Davis. There, Larry Schwankl, an irrigation specialist with cooperative extension, is testing and comparing different models of gypsum blocks and meters. The results of his work will be published in 1991.

Suggested Citation:"PART TWO: RESEARCH AND EDUCATION IN THE WESTERN REGION." National Research Council. 1991. Sustainable Agriculture Research and Education in the Field: A Proceedings. Washington, DC: The National Academies Press. doi: 10.17226/1854.
×

Outside the laboratory, gypsum blocks have been used at different times in several western states, but field results were sparsely documented until INFORM's field demonstrations in California in the 1980s. These provided the first comprehensive record of a systematic method for applying soil moisture data to a wide range of irrigation and other farm management decisions.

Paving the way to INFORM's study were several gypsum block field trials in the late 1970s that were organized by the Yolo County (California) Resource Conservation District to find a water management method that met farmers' practical needs. The director was Peter Mueller-Beilschmidt, an irrigation engineer and independent consultant from Davis, California. Mueller-Beilschmidt for many years had used blocks to evaluate sprinkler systems. He had also contributed to the technical improvement of gypsum block design and manufactured small quantities for his own engineering purposes.

During the course of these trials, Mueller-Beilschmidt developed a monitoring method specifically for surface irrigators, but it was equally applicable to sprinkler systems. Although the field trials went well, no resources were available to expand this initiative.

Field Demonstrations, 1984–1986

In 1983, INFORM learned of Mueller-Beilschmidt's work. Perceiving the value to farmers and the public of documenting and publicizing a promising conservation method, INFORM organized 3 years of gypsum block trials on 31 surface-irrigated fields (chiefly alfalfa, cotton, and tomatoes) in northern and southern sections of the Central Valley of California. (One sprinkler-irrigated almond orchard was also studied in the project's pilot phase.)

Cooperators were recommended by technicians or their neighbors. The 16 farmers who participated ranged in age from their 20s to their 80s and had different backgrounds, philosophies, and managerial styles. They owned or managed farms that averaged 1,000 to 1,500 acres in size.

Fields were selected by farmers and accepted by INFORM for testing if they met a bare minimum of practical criteria. No prior soil analyses were conducted, nor did the testing methods or measurements exceed, at any point, a precision that was easily achievable by the farmers themselves. The aim was not to control variables or make statistical inferences of cause and effect, but to demonstrate how farmers could manage water more efficiently within existing limits of information, equipment, and established (and diverse) farm routines.

Each field trial began with a check for uneven root zone wetting, which is a major cause of irrigation inefficiency and drainage buildup. As re-

Suggested Citation:"PART TWO: RESEARCH AND EDUCATION IN THE WESTERN REGION." National Research Council. 1991. Sustainable Agriculture Research and Education in the Field: A Proceedings. Washington, DC: The National Academies Press. doi: 10.17226/1854.
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TABLE 8-1 Water Distribution on 31 Surface-Irrigated Fields in California, Tested by INFORM, 1984–1986

Patterns of Soil Wetness After Irrigation

Number of Fields

Uniform saturation to 4-foot depth

7

Too wet before irrigation to judge

8

Underirrigated top-middle section(s)

9

Underirrigated end-middle section(s)

9

Underirrigated depth

2

Underirrigation of entire field

2

Total

37*

* Six fields were counted twice because distribution patterns varied in different sections.

SOURCE: Richardson, G., and P. Mueller-Beilschmidt. 1980. Winningwith Water: Soil-Moisture Monitoring for Efficient Irrigation. NewYork: INFORM.

quired for this analysis and later testing, a multiple-site monitoring system provided data from several points down the irrigation run on two strips in each field.

Of the 31 surface-irrigated fields studied, only 7 were found to be uniformly irrigated. Of the remainder, 16 had some sections that were underirrigated and some that were overirrigated. On these fields, locations near the water source were just as likely to be skipped by irrigation as locations near the drain ditch—which is contrary to common teaching and farmers' expectations. Eight fields were so heavily watered that distribution patterns were obscured altogether (the soils were continuously soggy) (Table 8-1).

Distribution patterns typically changed during the irrigation season and sometimes varied from one field section to another. Such complexities had diverse causes, including soil compaction and other poor soil conditions—as well as application rates that were poorly matched to soil types. These site-specific variations ruled out any single remedy for inefficient water use.

On several fields, where farmers' cooperation and logistics permitted, INFORM demonstrated how soil moisture data helped farmers spot and correct uneven distribution patterns. Then, on 21 fields, INFORM used soil moisture data to make scheduling changes and reduce water applications on test strips of under 1 to more than 17 acres. Water use, water cost, and yields on these strips were compared with the results of farmers' standard practices on each field's control strip.

Suggested Citation:"PART TWO: RESEARCH AND EDUCATION IN THE WESTERN REGION." National Research Council. 1991. Sustainable Agriculture Research and Education in the Field: A Proceedings. Washington, DC: The National Academies Press. doi: 10.17226/1854.
×
Findings

On 21 fields, INFORM found that the soil moisture method achieved water reductions ranging from 6 to 58 percent compared with farmers ' standard practices. Most reductions fell in the range of 20 to 40 percent. The highest reductions occurred on strips where both the application rate and the irrigation frequency were reduced (Richardson and Mueller-Beilschmidt, 1988).

Yields improved on 10 fields, remained the same on 6 fields, declined on 4 fields, and could not be assessed on 1 field. Of the 4 fields with lower yields, 2 cases were due to serious infiltration problems and two cases were due to irrigation delays caused by confusion about instructions to farmers.

The financial benefits from lower water costs on 13 test strips ranged form $1 to $90 per acre, depending both on the cost of the water and the size of the reductions. The median cost of water per acre-foot (whether purchased or pumped) was $17. The median benefit of water reductions was $10 per acre. On eight fields irrigated through large valves in underground pipelines, there was no practical way to measure outflow. Hence, neither the volumes of water reductions nor their economic values could be estimated except in percentages.

The financial benefits from higher yields on eight fields ranged from $5 to $126 per acre. All but one of these fields were planted with alfalfa, on which irrigations were reduced from two to one per monthly cutting cycle. On two more fields (one alfalfa and one tomato), farmers reported improvements in yield quality on the drier test strips, but no quantitative evaluation was possible.

The combined benefits of water cost reductions and increased yield revenues ranged from $25 to $165 per acre. These occurred on the six fields where both benefits could be measured.

The documented financial benefits fell short of the potential for improvements indicated by INFORM's field data. On most fields, two or three seasons of gradual changes would be needed to fully realize this potential. Moreover, reduced labor time, better assessment of new field practices, better management of equipment, and other gains reported to INFORM by farmers could not be quantified, yet they appeared to be significant in persuading farmers of the benefits of monitoring soil moisture.

GYPSUM BLOCK PROGRAMS IN CALIFORNIA AND COLORADO

Since the mid-1980s, when INFORM completed its research, the use of gypsum blocks has spread to more than 170 farmers in California and Colorado. Their field records and innovations provide the first broad-scale

Suggested Citation:"PART TWO: RESEARCH AND EDUCATION IN THE WESTERN REGION." National Research Council. 1991. Sustainable Agriculture Research and Education in the Field: A Proceedings. Washington, DC: The National Academies Press. doi: 10.17226/1854.
×

TABLE 8-2  Gypsum Block Demonstrations in California in 1989

Field Trial Result

Number of Farmers

Total farmer participants

45

Water and energy savings achieved

 

High ($59/acre average)

12

Moderate ($11/acre average)

7

Low ($4/acre average)

8

Insufficient data to quantify

3

Full season used for observation and analysis

8

Underwatering or infiltration problem

3

Farmer not interested

4

SOURCE: California Association of Resource Conservation Districts. 1989. Gypsum block demonstration trial. Unpublished draft. Sacramento: California Association of Resource Conservation Districts.

documentation under commercial conditions of the economic and environmental benefits of systematic soil moisture monitoring on irrigated fields. Several private and public programs have contributed to this trend. Farmers' receptivity is largely due to rising energy and water costs.

The California Program, 1989–1990

SCS technicians in California watched INFORM's research with interest. At its conclusion they sought INFORM's assistance in training SCS staff to use and teach the gypsum block method. After 2 years of technology transfer involving more than three dozen additional field trials, SCS concluded that the method met farmers' needs.

In 1988, with SCS's technical input, the California Association of Resource Conservation Districts won a 2-year grant of $90,000 from the California Energy Commission to teach moisture monitoring to 100 farmers in north central California (SCS Area IV). This program is developing thorough documentation of field results and farmers' reactions (California Association of Resource Conservation Districts, 1989).

In 1989, all but 4 of the 45 farmers who participated in the California Association of Resource Conservation Districts program in 1989 were persuaded of the benefits of soil moisture monitoring and reported their plans to continue using gypsum blocks. Of these, about half realized significant energy and water savings during the instructional period (see high and moderate water- and energy-savings categories in Table 8-2). Most of

Suggested Citation:"PART TWO: RESEARCH AND EDUCATION IN THE WESTERN REGION." National Research Council. 1991. Sustainable Agriculture Research and Education in the Field: A Proceedings. Washington, DC: The National Academies Press. doi: 10.17226/1854.
×

the remainder gathered useful information about fields, crops, and practices and said they would try scheduling changes in 1990.

The water reductions, where measurable, averaged nearly 1 acre-foot per acre. About 7,000 acres are currently managed with gypsum blocks in California.

Colorado's Ogallala Program

Colorado's Ogallala region includes more than half a million irrigated farm acres in the state's eastern plains. Parts of this area contain soils with a high clay content. Other sections belong to the sand hill country where the leaching of farm chemicals into groundwater is of growing concern. Yuma County, one of the top corn-growing counties in the United States, is located in this region.

In contrast to the California program, which emphasizes surface irrigation and employs several monitoring sites per field, the program in Colorado has concentrated on center-pivot irrigation and uses only one or two monitoring sites per circle. This reduces the yearly cost of equipment and labor for monitoring to $0.50 per acre in most cases.

Beginning in 1986, the Ogallala Team of SCS initiated a soil moisture monitoring program for corn and wheat producers. The 1986 work on a few fields was followed by a broader educational effort in 1987. In that year, INFORM gave essential support in the form of equipment and technical advice. Simultaneously, WAPA began a pump-testing program that quickly expended to include soil moisture monitoring. Since then the SCS- and WAPA-supported programs have branched into integrated resource management (see above). WAPA considers these programs to be models for programs in neighboring states.

In three growing seasons, 1987 to 1989, moisture monitoring has spread to 65,000 irrigated acres in six Colorado counties (and 10,000 additional acres of dryland wheat). The affected acreage is probably much greater because many farmers use monitoring data from one or two center-pivot irrigation circles to manage several others. In general, farmers who monitor their fields cut back from a 90- to 100-day irrigation season to a 60- to 70-day season. Water and energy cutbacks exceeding 50 percent are not uncommon.

Bruce Unruh, a corn farmer who has been in the program since 1987, reports that he has had to “throw away all the things that you were taught about irrigation and start all over.” Spurred by discoveries made with soil moisture monitoring, he has adopted a variety of new practices on irrigated corn. These include slower rotations of his center-pivot sprinkler system, the elimination of irrigation prior to planting, earlier cutoff dates in the fall, and ridge-till cultivation (which reduces herbicide use).

Suggested Citation:"PART TWO: RESEARCH AND EDUCATION IN THE WESTERN REGION." National Research Council. 1991. Sustainable Agriculture Research and Education in the Field: A Proceedings. Washington, DC: The National Academies Press. doi: 10.17226/1854.
×

Unruh says that $70 per acre is a conservative estimate of his cost savings from reduced inputs alone. Compared with his pre-1987 practices, his per acre costs have dropped $30 because of energy use cutbacks, $30 because of lower fuel consumption, and $10 because of reduced applications of fertilizer and herbicides. When Unruh completes his present transition to low-energy precision application sprinkler technology, he can probably anticipate another $10 per acre savings in lower energy bills, according to a local technician. Moreover, Unruh identifies many other benefits of his “revolution” for which he does not have figures readily at hand. These include higher yields, lower labor costs, and less equipment damage.

Most irrigators on Colorado's eastern plains use electric pumps. In one county, Kit Carson, an added boost to the SCS- and WAPA-supported programs has come from the rural electric cooperative, K.C. Electric Association. A recent change in electricity rate structure gives farmers a powerful incentive to withhold irrigation as long as possible in the spring and to cut it off as early as possible in the late summer. The new system is most effective for both the utility and farmers when combined with soil moisture monitoring, so the K.C. Electric Association provides gypsum blocks to farmers to bring them into the SCS and WAPA programs.

The cooperative extension and state energy and soil conservation programs also have links with the SCS program. Governor Roy Romer has twice presented the state's farm energy conservation award to farmers who participated in this program.

A staff of four in six counties can no longer meet growing farmer demand for instruction in soil moisture monitoring. Both farmers and technical staff believe that at least half of the farmers in the Ogallala region of Colorado would adopt the method if they could observe its benefits on their own fields. These farmers would include the largest and best producers and would affect far more than half the region's irrigated acreage. The cumulative impact of their field-level changes could greatly reduce the region's energy use, slow the depletion of the Ogallala Aquifer, and curtail the runoff and leaching that degrade water quality.

THE ROLE OF EDUCATIONAL ADVISERS AND AGENCIES

SCS technicians in California and Colorado agree that soil moisture monitoring with gypsum blocks sells itself. However, they emphasize the importance of initial instruction that includes the following components as being essential for getting farmers to the takeoff point over one or two seasons:

  • demonstration on farmers' own fields;

  • one-on-one teaching (several meetings a year);

Suggested Citation:"PART TWO: RESEARCH AND EDUCATION IN THE WESTERN REGION." National Research Council. 1991. Sustainable Agriculture Research and Education in the Field: A Proceedings. Washington, DC: The National Academies Press. doi: 10.17226/1854.
×
  • farmer participation as early as possible in installing gypsum blocks and collecting readings; and

  • patience; farmers “look before they leap,” and it sometimes takes a while for them to respond.

Soil moisture monitoring opens a new world to both farmers and technicians, and they learn together. This creates a strong foundation for the development of integrated farm management plans based on site-specific conditions and farmers' actual questions and needs (Richardson et al., 1989).

PRODUCERS OF GYPSUM BLOCKS

There are several producers of gypsum blocks and meters in the United States, chiefly the following:

  • Beckman Industrial Corporation, Cedar Grove, New Jersey

  • Delmhorst Company, Towaco, New Jersey

  • Electronics Unlimited, Sacramento, California

  • Irrometer Company, Riverside, California

  • Soilmoisture Equipment Corporation, Santa Barbara, California

  • Soil Test Incorporated, Denver, Colorado

Different models of gypsum blocks and meters perform differently. No technical standards have yet been developed for evaluating and comparing their features.

Electronics Unlimited supplies the blocks and meters that were used in all of INFORM's work and continue to be used by SCS in California. The Delmhorst Company has been the leading supplier of the blocks and meters used in the program in Colorado.

THE PUBLIC ROLE

Soil moisture monitoring is a practical route to lower production costs for irrigated farms and more effective protection of the environment in the western United States. It deserves increased public support of several kinds.

  • Research is needed to establish technical standards to enable farmers and technicians to choose wisely among the available soil moisture sensors, which vary in sensitivity, uniformity, longevity, and price.

  • Field demonstrations targeted in areas plagued by drainage and contamination problems could help to identify practical applications of soil moisture monitoring as components of regional water quality plans.

  • The training of field staff in major federal and state agencies would give farmers much broader access to instruction in soil moisture monitoring.

Suggested Citation:"PART TWO: RESEARCH AND EDUCATION IN THE WESTERN REGION." National Research Council. 1991. Sustainable Agriculture Research and Education in the Field: A Proceedings. Washington, DC: The National Academies Press. doi: 10.17226/1854.
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  • Modest financial assistance to farmers during an initial instructional period of 1 or 2 years would encourage more farmers to try soil moisture monitoring. Once farmers see its benefits on their own fields, they are generally willing to carry the method's full costs.

REFERENCES

California Association of Resource Conservation Districts. 1989. Gypsum block demonstration trial. Unpublished draft. California Association of Resource Conservation Districts, Sacramento, Calif.

Richardson, G., and P. Mueller-Beilschmidt. 1988. Winning with Water: Soil-Moisture Monitoring for Efficient Irrigation. New York: INFORM.

Richardson, G., J. Tiedemann, K. Crabtee, and K. Summ. 1989. Gypsum blocks tell a water tale. Journal of Soil and Water Conservation 44:192–195.

Suggested Citation:"PART TWO: RESEARCH AND EDUCATION IN THE WESTERN REGION." National Research Council. 1991. Sustainable Agriculture Research and Education in the Field: A Proceedings. Washington, DC: The National Academies Press. doi: 10.17226/1854.
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9

Reactors' Comments

Research and Education in the Western Region

Dale R. Darling

Many of the processes proposed for changing agriculture, including low-input sustainable agriculture (LISA), sustainable agriculture, alternative agriculture, best management practices, integrated pest management, and integrated crop management, are used by many highly efficient, profitable farm operators today.

Agriculture was changing before LISA; however, the pace and intensity, as well as the focus, have quickened since LISA was introduced. Some of the products developed by DuPont involved in this change are described below:

  • methomyl (Lannate) was used for insect control in soybeans based on economic thresholds in the early 1970s; it is now referred to as integrated pest management;

  • linuron (Lorox) herbicide was used for no-till soybeans in the early 1970s:

  • chlorsulfuron (Glean) herbicide, the first of a family of new low-level, low-environmental-impact herbicides, is a virtually nontoxic crop protectant for cereals; and

  • low-level, low-environmental-impact pyrethroid insecticides, such as estenvalerate (Asana), are used along with low-level herbicides to reduce significantly the quantity of pesticides placed in the environment.

Through change comes opportunity. Industry looks forward to the challenges, changes, and opportunities for a more environmentally sound, so-

Suggested Citation:"PART TWO: RESEARCH AND EDUCATION IN THE WESTERN REGION." National Research Council. 1991. Sustainable Agriculture Research and Education in the Field: A Proceedings. Washington, DC: The National Academies Press. doi: 10.17226/1854.
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cially acceptable, and more profitable agriculture system for U.S. farmers and their customers, the consumers.

In reviewing these comments, the reader must keep in mind my biases about agriculture. First, agriculture is fundamentally sound and very productive, with abundant opportunities for improvement through scientific discoveries. However, the starting point for initiating change should be with the highly efficient, profitable, environmentally conscientious farmers who have incorporated the results of 90 years of agriculture research and education into their profitable enterprises. Second, to create change efficiently and effectively, all of those involved in the input side of agriculture should be included in the process along with those who envision the need for dramatic changes.

REACTIONS

Below are some of my general reactions to the chapters presented in the section, “Research and Education in the Western Region.”

  • In general, there is no argument with the concepts and principles presented in the sustainable agriculture focus.

  • There appears to be more of a spirit of cooperation developing between most facets of agriculture and production; research and education; and government, industry, and producers.

  • Some still need to understand that crop protectants are marketed for the purpose of managing excesses in pest populations; they are tools, like a plow, a cultivator, or a hoe.

  • A team approach to research, demonstration, education, marketing, and production is the most economical and rapid method for creating change. The highly efficient, profitable farming enterprises most rapidly adopt new ideas.

The following are specific responses to the chapters in this section.

In their opening, John Gardner and colleagues (“Overview of Current Sustainable Agriculture Research”) asked, “if sustainable agriculture is so good, why is it so controversial? ” The concepts presented in that chapter are on target in relation to the title. However, if the leading question was answered, I missed the point. It is possible that the controversy Gardner and colleagues referred to is a result of the lack of communication between those involved in the established systems of research, education, and production and those desiring to change the systems.

Robert Papendick, in “STEEP: A Model for Conservation and Environmental Research and Education, ” showed that STEEP is truly a model of cooperation between producers, researchers, conservationists, ex-

Suggested Citation:"PART TWO: RESEARCH AND EDUCATION IN THE WESTERN REGION." National Research Council. 1991. Sustainable Agriculture Research and Education in the Field: A Proceedings. Washington, DC: The National Academies Press. doi: 10.17226/1854.
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tension personnel, commercial consultants, and retailers, as well as those involved in many production agriculture input industries, including the equipment, seed, fertility, and crop protection industries. The results are the proof.

The project described by Carol Shennan and colleagues in “Comparative Study of Established Organic and Conventional Tomato Production Systems in California: An Approach to On-Farm Systems Studies” could possibly benefit from involvement in the planning process by producers and input suppliers already involved in tomato production in the central coastal and interior Central Valley of California (Yolo, Sutter, and Sacramento counties). Those researchers who are currently involved in the project include a plant physiologist, a plant pathologist, a zoologist, an ecologist, as well as an economist. The model of cooperation between all entities presented by Papendick in the STEEP program should be considered.

I suggest that the project be discussed with commercial agronomists, consultants, and other specialists currently involved in commercial tomato production in these regions. They are valuable sources of experience and information.

Gail Richardson, in “Soil Moisture Monitoring: A Practical Route to Irrigation Efficiency and Farm Resource Conservation,” provided an excellent demonstration of what appears to be a relatively low-cost, low-technology, practical approach to measuring soil moisture and plant response.

The intriguing thing she noted is the involvement of farmers, researchers, and educators with the suppliers of the technology in the field. The approach to developing the technology, as well as the simultaneous transfer of the technology, is similar to the approach used in the agricultural chemical, seed, and fertilizer industries, as well as that demonstrated in the chapter by Papendick on the STEEP program.

In the presentation of Kevin Gamble at the workshop (not included in this volume), “A National System for Sustainable Agriculture Information Dissemination,” it was difficult to understand the technological elements of the concepts that he presented. It was easy to grasp the theories themselves. They should be carried out.

There is an important link in the technology transfer process that should be considered in the development of a sustainable agriculture system. Regardless of where farmers get their information, for example, media, extension, other farmers, commercial representatives, a local coffee shop, or field days, there is one vital last point where information is condensed and transferred: that is, the equipment, seed, fertilizer, and crop protection retailers; consultants; or contract applicators where farmers exchange their dollars for information, products, or services.

I hope all participants will find these suggestions constructive and helpful.

Suggested Citation:"PART TWO: RESEARCH AND EDUCATION IN THE WESTERN REGION." National Research Council. 1991. Sustainable Agriculture Research and Education in the Field: A Proceedings. Washington, DC: The National Academies Press. doi: 10.17226/1854.
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A Farmer's Perspective

Robert A. Klicker

I am pleased to be able to react to some of the information presented in this volume (see the chapters by R. James Cook, Gail Richardson, Robert I. Papendick, Carol Shennan, and Kevin Gamble). The information in these chapters was presented clearly and accurately and can be incorporated into use on my farms, which are located in four areas with different soil types and rainfall amounts. I am concerned that results of the type of research discussed in those chapters take years before they are available to farmers. The results of this kind of research should be directed and incorporated into complete farm systems as soon as possible after they become available.

James Cook's documented microbial research and his opinions on soil microbial action are the major key to sustainable agriculture. The bulletin “Long-Term Management Effects on Soil Productivity and Crop Yield in Semi-Arid Regions of Eastern Oregon” (Columbia Basin Agricultural Research Center, 1989) expands on Cook's points. This bulletin explains in detail the long-term soil depletion and reduced crop yield problems for which there have been no corrective solutions since 1931. Cook 's research is a major contribution to some of the corrective solutions that can be used in a complete farm system.

Gail Richardson's chapter documenting her 7 years of on-farm water conservation technology with the use of gypsum blocks is also a major key for sustainable agriculture. Richardson documented a 20 to 40 percent savings of water. She also discussed methods that can be used to inspire farmers to apply the information she has gathered to their irrigation techniques. She proved that these methods are an economic educational tool that can be widely accepted by farmers and that can help them to understand the movement of water, soil plow pans, or compaction and when there is too much or not enough water in the root zone.

STEEP coordinator Robert Papendick reviewed the excellent progress that has been accomplished in reducing soil erosion, which leads to improved water quality. I was also pleased to read a discussion of the plans for STEEP II research.

James Cook has stated it all correctly when he says, “Scientists are rewarded for discovering and working out mechanisms but not for carrying this technology into application.” Experience has proven that piecemeal, conflicting data will not build a sustainable agriculture system. All sustainable agriculture could be lost if complete farm systems research does not zero in on water harvesting, organic matter, and soil tilth research. A complete sustainable agriculture system (including use of the correct amount of

Suggested Citation:"PART TWO: RESEARCH AND EDUCATION IN THE WESTERN REGION." National Research Council. 1991. Sustainable Agriculture Research and Education in the Field: A Proceedings. Washington, DC: The National Academies Press. doi: 10.17226/1854.
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nutrients plus use of soil cation-exchange ratios, correct tillage, water, and air) promotes increased microbial biomass and increased organic matter. Organic matter has three times the water- and nutrient-holding capacity than clay does. Increases in organic matter promote higher yields and, often, higher-quality products. Because organic matter has a higher waterholding capacity, soils with good organic matter levels are less likely to erode. I know from my own and my neighbors ' soil tests that organic matter levels can be increased slowly and systematically by using commercial fertilizers and incorporating stubble with the correct conventional tillage tools. For each farm system, of course, there are slight variations in the methods that are used to stop erosion and increase organic matter. However, many of the basic methods stay the same.

Soil tests were performed on 15 different fields at three separate farms. These fields have had a definite, substantial increase in organic matter in 4 to 5 years. The normal erosion on these fields, which have 10 to 40 percent slopes, has been completely controlled without the loss of yield.

It is my opinion that the entire U.S. agricultural community should move toward the complete farm research system concept, incorporating James Cook's research, Gail Richardson's water conservation research, farmers' own on-farm research, and other existing technologies. Successful sustainable agriculture can be achieved by working to increase organic matter and the microbial biomass, by correcting soil tilth, and by stopping erosion while using conventional fertilizers and tillage tools. To accomplish this, the valuable information from the scientific community that is presented in this volume must be coordinated and shared with U.S. farmers in a more timely fashion.

REFERENCE

Columbia Basin Agricultural Research Center. 1989. Long-Term Management Effects on Soil Productivity and Crop Yield in Semi-Arid Regions of Eastern Oregon. Bulletin No. 675. Pendelton, Oreg.: Agricultural Research Service, U.S. Department of Agriculture, and Oregon State University Agricultural Experiment Station.

Suggested Citation:"PART TWO: RESEARCH AND EDUCATION IN THE WESTERN REGION." National Research Council. 1991. Sustainable Agriculture Research and Education in the Field: A Proceedings. Washington, DC: The National Academies Press. doi: 10.17226/1854.
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Sustainable Agriculture Research and Education in the Field: A Proceedings Get This Book
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Interest is growing in sustainable agriculture, which involves the use of productive and profitable farming practices that take advantage of natural biological processes to conserve resources, reduce inputs, protect the environment, and enhance public health. Continuing research is helping to demonstrate the ways that many factors—economics, biology, policy, and tradition—interact in sustainable agriculture systems.

This book contains the proceedings of a workshop on the findings of a broad range of research projects funded by the U.S. Department of Agriculture. The areas of study, such as integrated pest management, alternative cropping and tillage systems, and comparisons with more conventional approaches, are essential to developing and adopting profitable and sustainable farming systems.

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