ECONOMIC-ENVIRONMENTAL TRADEOFFS AMONG ALTERNATIVE CROP ROTATIONS

Simulated long-term impacts of different cropping systems are evaluate d and analyzed in terms of the tradeoffs among net returns and differe nt components of environmental quality. The cropping systems are model ed after the BARC Sustainable Agriculture Demonstration Farm. EPIC was used to obtain crop yields, soil erosion, and the environmental fate of nitrogen, phosphorous, and herbicides in response to weather and ma nagement practices over a simulated 30 year period. This procedure pro vides a way to estimate the environmental impact of cropping rotations , and to analyze the tradeoffs between competing objectives, whether t hey are farm income, erosion control, or the reduction of multiple haz ards. The results indicate that the no-till rotation provides the grea test net returns, followed by the conventional rotation, The net retur ns on the two cover crop rotations are lowest. In terms of environment al impacts, no-till rotation dominates all other rotations with lowest nitrogen loss, and the covercrop rotations perform best in terms of e rosion and phosphorous loss. However because herbicides are necessary to control weeds in no-till, the pesticide hazard index is very high, suggesting a tradeoff between pesticide hazard and other environmental considerations. To provide decision makers with better information, a n environmental hazard index was constructed to analyze the tradeoffs between potential chemical contamination and net returns, Depending on preference structure, any one of three rotations could be preferred: no-till; manure at medium application rates; and cover crop without fe rtilizer.