Enhancing soil nitrogen mineralization and corn yield with overseeded cover crops

ABSTRACT:

Early in the growing season, an adequate level of mineralized soil N is essential in order to obtain optimum corn (Zea mays L.) growth and productivity. In Michigan, soil N sufficiency is often determined using the pre-sidedress nitrate test (PSNT) at stage V-6 of corn growth. The Living Field Laboratory (LFL) is a long-term cropping systems experiment established in 1993 at Hickory Corners, MI. The design is a split-block with in a split-plot. Main plots are commercial fertilizer vs. dairy manure compost as a nutrient source. Sub-plots are the entry points in a corn-corn-soybean/Glycine max (L.) Merr.J-wheat (Triticum aestivum L.) rotation, and continuous corn. These are further split so that each entry point is grown with or without an overseeded cover crop. By 1995, the third year of the rotation, rotation as well as cover crop influenced the rate of N mineralization at PSNT sampling. Red clover (Trifolium pratense L.) residue following wheat provided both the earliest and highest amount of mineralization, and the highest yield for a succeeding corn crop.