Soil and Water Quality An Agenda for Agriculture (1993) / Chapter Skim
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11 Manure and Nutrient Management
11 Manure and Nutrient Management
Pages 399-416
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From page 399... ...
Its organic matter content is double the amount of soil humus annually destroyed in growing the Nation's grain and cotton crops (U.S. Depall~l~ent of Agriculture, 1938:445~.
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From page 400... ...
Equally spectacular achievements have been realized in the production of highly effective phosphorus fertilizers from rock phosphates. Benefits of Manure Application Even though fertilizer prices have increased considerably in recent years as a result of increasing energy costs, in many instances they remain lower than the cost of handling animal manures.
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From page 401... ...
For dairy cattle manure, as much as one-half or two-th~rds might be voided on pastures, although the trend TABLE 11-1 Manure and Its Associated Nutrient Content Millions of Metric Tons (dry weight) Total Source Manure Nitrogen Phosphorus Potassium Cross and Byers (1990)
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From page 402... ...
of dry manure produced, Van Dyne and Gilbertson (1978) estimated that 47 million metric tons (52 million tons)
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From page 403... ...
dipping vats may contribute to surface water and groundwater contamination. Manure accumulations around livestock watering locations, intermittent-use stock pens, and livestock grazing operations that occur on areas ranging from sparsely grazed rangelands to intensively grazed pastures may also influence surface water and groundwater quality (U.S.
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From page 404... ...
Handling and Application Costs High labor requirements for manure handling, the increased travel distances required to spread manure, and reduced opportunities for using manure as a resource on farms have tended to increase the cost of using manure as a nutrient source. Investigators have developed management systems that reduce the amount of labor required to handle manure and that increase its nutrient value.
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From page 405... ...
. TABLE 11-3 Quantity of Livestock or Poultry Manure Needed to Supply 100 kg of Nitrogen over the Cropping Year with Repeated Applications of Manure Number of Years Quantity (metric tons)
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From page 406... ...
Historically, manure application rates have mainly been based on nitrogen loading rates, with little attention paid to phosphorus accumulation. However, with the growing environmental concern associated with phosphorus in surface water supplies, pressures are mounting for limiting or even banning phosphorus additions to soils that exceed a certain level of plant-available phosphorus on the basis of a soil test.
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From page 407... ...
This situation threatens local and regional environments because southeastern Pennsylvania agricultural land is a major source of the nutrients and pesticides that enter the Chesapeake Bay (Young et al., 1985~. The volume of manure produced in areas where livestock production is concentrated may well exceed the area of- cropland available on which to apply manures at rates that minimize the potential for surface water or groundwater degradation.
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From page 408... ...
also estimated the ratio of manure production to land area in the United States. The average ratio of economically recoverable manure weight to cropland area and improved pasture averaged only 0.27 metric tons of manure per hectare (0.12 tons/acre)
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From page 409... ...
Figure 11-3 shows manure production and nitrogen concentration (on an as-voided basis) within various intensive animal production systems versus extensive livestock production systems as a function of animal density and spacing per unit live weight (U.S.
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From page 410... ...
Although some manure transactions occur now, there is not a flourishing market for manure, and the potential for marketing excess manure nutrients with a positive return to farmers is limited. Considering the volume of the excess manure on farms in southeastern Pennsylvania, Young and colleagues (1985)
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From page 411... ...
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From page 412... ...
Several states and local entities do have groundwater protection requirements. For example, the Texas Water Commission regulation that governs confined, concentrated livestock and poultry feeding operations includes groundwater protection for lagoons and holding ponds.
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From page 413... ...
to develop and extend economic guidance for land application of manures, including soil and manure testing to define appropriate application rates and information about nutrient release rates to allow efficient and economically viable use of manures. These efforts must include quantification of the magnitude of nutrient losses from lagoons, storage tanks, and land application as a function of design, operation, and climatic variables to develop nutrient management plans and nutrient mass balance models.
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From page 414... ...
determined that nutrient losses could be reduced about 10 percent with negligible impacts on net farm economic returns by using manure storage, the more even application of manure on croplands, and changes in the intensity of crop rotation. Given the fact, however, that the additional income generated by adding a cow exceeds the additional expenses associated with disposing of the extra manure when society bears the pollution impact, overapplication of manure nutrients is economically rational (Young et al., 1985~.
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From page 415... ...
Manure is widely used as an organic fertilizer in many areas. Certain types of manure also may receive limited use in specialized situations as animal feedstuffs, as a substrate for anaerobic digestion to produce methane gas, or as a fuel for combustion or gasification for electric power generation.
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