Agricultural runoff has dramatically altered life in the shallow waters of the Gulf of Mexico. Hypoxia, in essence the cutting off of oxygen, has choked off aquatic life in the Gulf. Continued practices will essentially kill off life, and the massive fishing industry will die with it. In the photo below, you can see the massive amount of farmland drained by the Mississippi River system into the Gulf.
Cover crops can significantly reduce the amount of runoff, particularly nitrate, into the streams and rivers that supply the Gulf from the Mississippi River. In fact, in a study conducted by Eileen Kladivko (Purdue Univ.), Tom Kaspar (USDA-Iowa) and others, they estimate that the adoption of cover crops more uniformly by farmers, in just five Midwest states, can reduce the amount of nitrates by an estimated 20%. These five states (Ohio, Indiana, Illinois, Iowa and Michigan) are responsible for almost HALF of the nitrate loading in the Gulf.
The study looked only at cereal rye as a possible cover crop. Use of annual ryegrass has benifits over cereal rye.
- It has deeper roots, which means deeper nutrients and moisture for corn and soybeans. Deeper roots also means less compaction
- Annual ryegrass is a scavenger of nitrogen. In addition to saving on inputs of fertilizer, annual ryegrass stores nitrogen and then yields it to the corn in the spring, when the grass is killed.
Check out the other differences between annual ryegrass and cereal rye in this publication. Among other things, cereal rye can tie up nitrogen too long, thus requiring added inputs for corn growth. And, cereal rye can grow too much on the surface (6 -7 feet) and thus make it difficult to plant into in the spring. Annual ryegrass, on the other hand, releases nitrogen in time for the corn to use efficiently. And it’s root mass creates more biomass in the soil, thus creating more food for worms and microbes, more organic matter and healthier soil.