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Agricultural Development and Environmental Research American and Czechoslovak Perspectives: Proceedings of a Bilateral Workshop (1987) / Chapter Skim
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'A CONCEPTUAL FRAMEWORK FOR ANALYZING AGRICULTURAL AND ENVIRONMENTAL CONCERNS'
Pages 5-14

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From page 5...
... Agricultural systems developed over wide ranges of climate and soil resources have achieved remarkably high levels of production of food, feed, and fiber to provide relative security for an ever-increasing world population. With few exceptions, high levels of production are achieved by bringing agronomic practices into harmony with natural processes of the biosphere.
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From page 6...
... These technologies include remote sensing, computerized data management systems, analytical and monitoring equipment, chemical and biochemical techniques and, perhaps most importantly, systems analysis. CONCEPTUAL FRAMEWORK Early conceptual models of ecosystems developed by Dokuchaev and Jenny emphasized the factors controlling development of soil properties, referred to as state factor controls.
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From page 7...
... DRIVING VARIABLES PARENT MATERIAL CLIMATE BIOTA TOPOGRAPHY Rangeland Grazing Species Nutrient Input Fire MAN \ Cropland Cultivation Fallow Crop Selection Residue Management Water Management Nutrient Inputs Fire Harvest Forests Seeding and Planting Site Preparation Watershed Management Fire Harvest Initial time TIME Present or Future PROCESSES ENERGY INPUTS AND TRANSFORMATIONS • Radiation • Nutrient Cycling • Primary Production Immobilization • Decomposition Mineralization • Weathering Translocation • Transport Erosion Gaseous Leaching Runoff DEVELOPMENT OF ECOSYSTEM PROPERTIES • Vegetation • Consumers • Soil Base Status Texture Organic Matter Phosphorus Sulfur Nitrogen Salinity FIGURE 1 properties. Relationships among driving variables, processes, and ecosystem
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From page 8...
... Specific hypotheses involve the particular effects of driving variables on various processes and thereby on the dynamics of ecosystem structure over time. This approach requires a thorough understanding of processes over a wide range of controls.
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From page 9...
... These concepts account for variability in soil organic matter composition and set the stage for predicting the relationship between the cycling rates of N, S, and P in soils. Since the behavior of S is intermediate -- between that of N and P -- a study of S transformations helps to explain differences in quality of soil organic matter.
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From page 10...
... Organic P existing in chemically or physically protected forms may be slowly mineralized as a by-product of overall soil organic matter mineralization or by specific enzyme action in response to the need for P Therefore, organic matter turnover as well as solution Ptconcentration and the demand for P by microbial and plant components will be factors controlling the lability of P0 (McGill and Cole 1981)
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From page 11...
... REGIONAL ANALYSIS OF SOIL ORGANIC MATTER, NUTRIENT AVAILABILITY, AND SOIL PRODUCTIVITY: THE GREAT PLAINS A study of management effects on soil organic matter and productivity in the semi-arid Great Plains of North America exemplifies the application of this conceptual framework. The accumulation of organic matter in grassland soils over a wide range of temperature and moisture gradients in the Great Plains is an excellent example of state factor controls on development of an important ecosystem property.
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From page 12...
... The analysis of changes in levels of organic C, N, S, and P in grassland soils placed under cultivation confirmed concepts of state factor control over soil processes that were developed in early studies of topo- and chronosequences formed over geological time periods. Major controls on key chemical, physical, and biological processes were identified to provide linkages for interpretation across different scales of time and space.
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From page 13...
... The ratio NPP/CDP indicates the potential for carbon stabilization in the soil. The lower panel shows predicted soil carbon levels to 20 cm for sandy-textured grassland soils.
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From page 14...
... Proceedings XIII Congress of the International Society of Soil Science (in press)
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Key Terms

  • soil organic
  • driving variables
  • nutrient cycling
  • grassland soils
  • phosphate ions

  • soil solution
  • nutrient elements
  • key processes
  • matter levels
  • state factor

  • factors controlling
  • soil properties
  • ecosystem processes
  • matter dynamics
  • nutrient availability

  • key chemical
  • ecosystem structure
  • ecosystem properties
  • management effects
  • agricultural production

  • conceptual models
  • controlling factors
  • wheat fallow
  • factor controls
  • simulation models

  • biogeochemical cycles
  • primary production
  • labile inorganic
  • process controls
  • organic soil


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