Annual ryegrass used as a cover crop with no-till corn can out-produce conventionally tilled acres by an average of 50 bu/acre in droughty conditions. University of Illinois extension soil scientist Mike Plumer and southern Illinois grower Ralph “Junior” Upton have compared conventionally tilled with no-till acreage with and without cover crops.

Corn yields on natural hardpan soils seem to improve after about three years of planting annual ryegrass with continuous no-till. In 2006, with normal rainfall, no-till and annual ryegrass were compared to conventional tillage in replicated plots. Corn yielded 102 bu/acre in conventional plots; 155.7 bu/acre in cover-crop plots. In 2007, annual ryegrass no-till plots yielded 70 bu/acre more than conventional plots.

According to Dan Towery, Ag Conservation Solutions, southern Illinois soil has a hardpan at about 16", but annual ryegrass roots grow to 3' and break through that layer, creating macropores when the roots decay. That allows corn and soybean roots to follow the ryegrass root paths the next growing season to reach soil moisture not normally available.

Ryegrass also helps recycle nitrogen in the soil, then releases it to the row crop after burndown the following spring, Towery says. Plumer adds that the ryegrass can also “mine” nutrients, including phosphorus and potassium, from deep in the soil.

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