A potentially record-setting U.S. corn harvest is underway. Many farmers can attribute the use of cover crops as one of multiple best management practices (BMPs) that help them increase yield year after year. Combined with BMPs of The Fertilizer Institute’s 4R Nutrient Stewardship program that promotes the application of nutrients at the right source, right rate, right time and right place, farmers further ensure top production.
“Interest in cover crops has grown immensely the past few years,” said Eileen Kladivko, an agronomist and cover crops specialist with Purdue University. “Cover crops are an integral part of modern, sustainable agriculture. With improved plant genetics, synthetic fertilizers, pesticides and machinery helping to increase yields, but sometimes masking soil degradation, cover crops become an important part in helping to improve underlying soil resources and in obtaining the full potential benefits from additional crop inputs.”
She adds that different cover crops provide different benefits and growers must decide what their primary objectives are when selecting cover crops.
“Cover crops are often planted for their benefit to the soil or environmental quality and not for harvest,” Kladivko added. “Some may be suitable for grazing or haying, but this means they should be managed as forage crops.”
In general, she says the benefits of cover crops fall into these categories.
- Scavenge or, “trap” nitrogen and protect water quality – the crops trap residual soil nitrate to prevent it from leaching into groundwater.
- Produce nitrogen – legumes fix atmospheric nitrogen for their own use. Once terminated, much of the nitrogen is released to succeeding crops as residues decompose.
- Prevent erosion – the crops cover the soil surface to protect against water and wind erosion.
- Build soil quality and/or recycle nutrients – cover crops improve soil’s physical properties, increase soil’s organic matter and increase soil’s biological activity.
- Suppress weeds – some crops can suppress weeds by competition, shading or allelopathy.
- Enhance wildlife habitat – cover crops can provide water, cover and food for wildlife and increase landscape diversity.
These benefits will vary from year to year, depending on weather and the amount of growth of the cover crop, she advises.
“After a drought year, it’s even more important to plant a cover crop in the fall,” Kladivko adds. Once the rains return, the cover crop will be there to scavenge some of those nutrients not used by the cash crop.”