Are cover crops worth it? It depends
Society is becoming increasingly more aware of the environmental consequences of agricultural production. Farmers today are under increasing pressure to adopt more sustainable farm management practices. One method to improve the sustainability of crop production is the use of cover crops. Cover crops are planted "off-season" to provide agronomic and environmental benefits. The objective of this research is to quantify the impacts of cover crops and determine where and under which management practices cover crops provide the greatest benefit. Management practices include different crop rotations, tillage practices and residue removal rates. This paper will focus on soil erosion, nitrate leaching and soil organic carbon. To quantify the impact of cover crops, a dummy variable model was used to estimate the amount of soil erosion, nitrate leaching and soil organic carbon change for a combination of different management practices on soils with different land capability class ratings. Once the environmental outcomes have been determined, the benefits of cover crops can be quantified. Data for the environmental outcomes are simulated by the Landscape Environmental Assessment Framework (LEAF). To determine if cover crops are worth the cost, estimates for the price of soil erosion, nitrate leaching and soil organic carbon are combined with the environmental outcomes. From this analysis we find that: (1) cover crops improve environmental outcomes (2) reduced till benefits more from cover crops than no till (3) continuous corn rotations benefits more from cover crops than corn soybean rotations (4) soils with higher land capability class ratings benefit the most from cover crops (5) cover crops are needed to maintain positive soil organic carbon for medium residue harvest and high residue harvest (6) considering only the nutrient benefits of reduced soil erosion, reduced nitrate leaching and increased soil organic carbon rarely justifies the cost of cover crops (7) for high residue harvest, the social benefits of cover crops always exceed the cost.
Tyner, Purdue University.
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