Soybean and Corn Growth As Influenced by Methods for Controlling Previous Cover Crop, Including Winter Kill, Flaming, Disking, and Crimping.

Development of a more diverse crop rotation in eastern Nebraska, and reduction of tillage in organic cropping systems were two objectives that inspired this 2-year study. However, including winter wheat in a rotation presents the complication of how to prudently utilize the growing period available between winter wheat harvest (July) and winter. How to best manage the cover crop for a healthy successive row crop is also a challenge. This study focused on how over-winter cover crop species and kill method impacted the following annual warm-season row crop of either corn (Zea mays) or soybean (Glycine max). The study included a combination of cover crop species and cover crop termination techniques (winter kill, roller-crimping, disking, and flaming). After harvesting winter wheat, the following cover crops were planted: buckwheat (Fagopyrum sagitattum), berseem clover (Trifolium alexandrinum L.), spring oats (Avena sativa), soybean, sudangrass (Sorghum bicolor spp. Drummondii), winter rye (Secale cereale), hairy vetch (Vicia villosa), red-yellow clover mix (Trifolium pratense and Melilotus officinalis), triticale (Triticale hexaploide Lart.), and a no-cover control. The cover crop species that were expected to winter kill were buckwheat, berseem clover, spring oats, soybean, and sudangrass; species not expected to winter kill were winter rye, hairy vetch, red-yellow clover mix, triticale, and no cover. The cover crop species not winter-killed were controlled in spring prior to row crop planting using flaming, roller-crimping, or disk tillage. The winter kill and spring disk treatments produced the highest average yields in corn and soybean, at 6.83 Mg/ha (corn) and 2.66 Mg/ha (soybean). The roller-crimper and flaming treatments both reduced yields by 68% and 62% in corn, and by 36% and 27% in soybeans, respectively. Differences in weed control and crop population were the apparent causes of the yield reductions.