摘要：Recent trends in livestock concentration suggest that there may be an increasing risk of water pollution from manure applications. These trends in livestock operations may be offsetting improvements in commercial fertilizer management that have the potential to reduce the risk of water pollution. This conclusion was derived by tracking excess nutrient trends between 1996 and 2002 and by examining measures of economic performance for livestock farms. First, a link was established between the expansion of AFOs (Animal Feeding Operations) and excess nutrients from commercial fertilizer and manure sources. Second, technical efficiency was measured in order to identify whether technical efficiency explains structural change and in order to see whether accounting for "bads" is likely to change technical efficiency measures. In general, the results suggest that adjusting the performance measures to include excess nutrients as a "bad output" would tend to widen the gap between high and low performance farms in the north while the results of such an adjustment are less clear in the south.
