Ph.D. Level Student
Southern Illinois University Carbondale
Advised by Dr. Amir Sadeghpour
Wheat Cover Crop Management Impact Lingers After Corn Harvest In A Corn-Soybean Rotation
Illinois is the largest producer of soybean (Glycine max) and the second largest producer of corn (Zea mays) in US. The corn-soybean cropping rotation system is very popularly in Illinois. Studies done in Southern Illinois have shown nitrate-N leaching to be high after cash crop harvest. Winter cereal cover crops (WCCC) are recommended as best in-field management practice to minimize nutrient loss. Winter cereal cover crops including wheat (Triticum aestivum L.) are often terminated 3-4 weeks prior to planting corn. Delaying termination increases N uptake and decreases N leaching potential but could immobilize N during corn growing season. A two-year field trial was conducted to evaluate the lasting effect of late terminated wheat practice beyond corn in a cash crop-cover crop rotation cropping system. Experimental design was randomized complete block design with split plot arrangements and four replicates. Main plots were wheat CC treatments [(I) fallow (no-cover crop control) and (II) late termination], and subplots were N treatments including (I) 0 (no-N control), (II) 224, and (III) 330 kg N ha-1. Corn population was higher in the fallow at the 0N treatment; N fertilization resulted in similar corn population between fallow and wheat cover crop treatment. Corn grain yield was lower in wheat cover crop than the fallow treatment in 0N and 224 kg N ha -1. N balance in the fallow plots were lower than terminated wheat in all N rate treatments higher N uptake in fallow plots than wheat terminated plots. Lower biomass in the following rye in rotation was observed in wheat terminated plots indicating that wheat effect continued into the rye growing phase. Soybean yield was higher in terminated wheat than fallow suggesting a need for economic assessment into yield loss during corn phase vs. yield gain in soybean phase by late termination of wheat.