The impacts of continuous corn and a corn-corn-soybean-wheat rotation grown under various management schemes on nitrate leaching, soil physical characteristics, and net returns.

摘要

A long-term rotation study on Oshtemo and Kalamazoo sandy loamy (coarse-loamy, mixed, mesic Typic Hapladaulfs) at the W. K. Kellogg Biological Station near Hickory Corners, MI was established in 1993 to compare various physical and economic parameters of a corn-corn-soybean-wheat rotation to those of continuous corn under various management systems. The organic (O) and integrated compost (IC) systems used compost as the external nutrient source while the integrated fertilizer (IF) and conventional (C) systems used synthetic fertilizers. Both systems receiving compost had lower nitrate leaching rates than the systems using fertilizer. In the IC system 1st year corn leached more nitrate (50 kg N ha−1yr −1) than 2nd year corn (35 kg N ha−1 yr−1), soybean (34 kg N ha−1yr −1) continuous corn (26 kg N ha−1yr −1), or wheat (17 kg N ha−1yr−1 ). In the IF system the nitrate leaching rates of 1st year corn (59 kg N ha−1yr−1), 2 nd year corn (67 kg N ha−1yr−1), and continuous corn (57 kg N ha−1yr−1) were greater than the leaching rates of soybean (39 kg N ha−1 yr−1) or wheat (20 kg N ha−1yr −1). Net returns to land and management expertise were highest in the O treatments ({dollar}359–398 ha−1) due to the premium prices associated with organic crops. Within the normally priced crops the IF corn-corn-soybean-wheat rotation without cover crops had the highest net returns ({dollar}155 ha−1) followed by the IF rotation with cover crops ({dollar}128 ha−1) and the C rotation ({dollar}116 ha −1). The IC continuous corn had the lowest net returns both with cover crops ({dollar}15 ha−1) and without cover crops ({dollar}10 ha−1). This research demonstrated that a corn-corn-soybean-wheat rotation had higher net returns than continuous corn while building soil quality and reducing environmental impact from nitrate leaching. The use of compost enhanced the soil quality effects but would not be effective in rotations with multiple years of corn.