In the next month, all that lush annual ryegrass will become history…as you’ll have to terminate the cover crop to make way for soybean and corn seeds. But “history” is a relative term…in fact, the residue of the grass will quickly decompose, giving the precious nitrogen it has stored up to the new plants.
Here’s a website with specific data about the proper way to burndown annual ryegrass.
While the dead foliage provides nitrogen for the corn and soybean sprouts during critical times in the late spring and early summer months, the roots produced by the ryegrass will also play an important role, in two ways. First, as the roots decay, they’ll provide organic matter for the soil, and nutrition for the bacteria, microbes and earthworms that help create healthy soil. Secondly, and nearly as important: the channels created deep into the subsoil by the annual ryegrass roots allows corn roots to sink equally deep, thus giving the crop a summer-long supply of moisture and nutrients deeper in the soil profile.
Especially in dry years, annual ryegrass cover crops will give your corn harvest a huge boost. Growers regularly find that cover crop acreage outperforms no-till and conventional tillage acreage by as much as 100 bu/ac!