The efficacy of controlling phosphorus loading: the case of management-intensive grazing§

Consolidation in US agriculture has led to fewer, larger farms. In the case of dairy in the Northeastern US, higher concentrations of animals near large population centers pose water quality problems that can be attributed to excessive soil nutrient levels. While new environmental policies and regulations are being developed and implemented to help manage such problems, research to determine the efficacy of alternative dairy production systems is needed. The research reported in this paper makes use of stochastic dynamic programming to determine optimal stocking densities, milk production levels, and feed rations for a hypothetical dairy farm using management-intensive grazing. A key feature of the model is that financial disincentives are placed on excessive accumulation of phosphorus in the farm’s soils. The results show that under optimal management the cost of reducing soil phosphorus to acceptable levels across all states of nature modeled is approximately $524 per hectare per year. The optimal farm management strategy is to rapidly reduce the size of the dairy herd (as opposed to feeding for a lower level of milk production per cow) until soil phosphorus levels are under control. # 2003 Elsevier Ltd. All rights reserved.