Laura Snively VanDyke
Master's Thesis submitted to the Faculty of the Virginia Tech in partial fulfillment of the requirements for the degree of
Master of Science
Agricultural and Applied Economics
Darrell Bosch, Co-Chair
James Pease, Co-Chair
January 31, 1997
This study provides an environmental and economic analysis of the ability to reduce potential nitrogen loadings to water bodies through the implementation of nutrient management plans on livestock farms. Study results indicate that nutrient management plans do result in significant reductions while maintaining or increasing farm income. Nutrient management plans on the four case farms reduced mean nitrogen losses by 23 to 45 percent per acre while increasing net farm income from $395 to $7,249.
While reducing excess nitrogen applications with the implementation of nutrient management plans achieved significant reductions in potential nitrogen losses, further reductions may be achieved through farm level planning. After achieving initial reductions through the elimination of excessive nutrient applications, variation in application rates of organic and inorganic fertilizers across soils may become important in achieving further reductions in nitrogen loss. Study results suggest that it may be beneficial to apply higher rates of manure on soils and slopes less susceptible to nitrogen losses in order to reduce applications elsewhere. Increased nutrient losses on such fields may be more than offset by reductions on soils more susceptible to nutrient losses. Linear programming results for the Shenandoah Valley Dairy show that nitrogen losses could be reduced up to 44 percent below pre-plan losses with no impact on farm net economic returns. However, if nitrogen loss restrictions were instituted beyond this level, the impact on farm income increases significantly. After-plan nitrogen losses can reduced up to 52 percent, but farm returns decrease by 56 percent.
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