Use of a Rye Cover Crop following Corn in Rotation with Soybean in the Upper Midwest

There is a need for improved soil and water conservation in the corn (Zea maysL.)–soybean [Glycine max(L.) Merr.] rotation common to the upper Midwest, and an appropriate cover crop may fulfill this need. A corn–soybean rotation that included a rye (Secale cerealeL.) cover crop was studied at two Minnesota locations in 2002 and 2003 to evaluate rye management method and timing for no‐till soybean production. Fall‐planted rye following corn harvest at Waseca and Rosemount was managed the next spring by: (i) mowing once, (ii) mowing twice, (iii) applying glyphosate herbicide once, (iv) applying herbicide twice, and (v) mowing once followed by applying herbicide, with four mow dates beginning 1 May separated by approximately 1 wk. Rye regrowth after mowing but before stem elongation in early to mid‐May was similar to that of uncut rye but decreased dramatically when mowed at anthesis in early June. At Rosemount, low weed populations and the presence of the rye cover crop, when properly managed, had only a minimal affect on soybean yield, resulting in the one‐pass mowing system being equally profitable as the no‐rye two‐pass herbicide system. At Waseca, where weed pressure was high, the rye cover crop treatments without subsequent herbicide application as well as the early one‐pass herbicide applications did not provide adequate control, making these systems less profitable. Our research indicated soybean yields following a rye cover crop were often comparable to yields where no rye cover crop was grown, but economic returns were usually reduced.