Now that the snow is coming off farm fields, you may notice some plants starting to green up. This new growth, sometimes mistaken for weeds, is a “crop” intentionally planted in the fall and is referred to as a cover crop.
A cover crop is a crop grown for the protection and enrichment of the soil. It is an additional crop that farmers plant into either annual or row crops in a way that this new crop will be growing after the initial crop is harvested.
Cover crops are a best-management practice that farmers use to improve the health of the soil in their fields. Cover crops are sometimes referred to as green manure and living mulch. Regardless of what you call them, they have the potential to provide multiple benefits in a cropping system. Plus, cover crops can provide environmental benefits.
Cover crops aid in reducing and even preventing soil erosion, improve the soil’s physical and biological properties, supply nutrients to the growing crop and the many microorganisms that live in the soil, suppress weeds, improve the availability of water to growing plants especially under drought conditions, break pest cycles and help maintain biodiversity in crop fields.
In central New York, cover crops established after corn silage or soybeans are very effective. When corn silage is harvested, the majority of the plant is removed from the field. This leaves only a small amount of the stem remaining and very little soil coverage. When corn is harvested for grain, only the ears are removed and the corn plant is left to cover the ground to protect the surface. A cover crop following corn silage and even corn for grain helps protect the bare areas of the soil surface.
In soybeans, the seed pods are harvested with only the stems remaining in the field. When ready for harvest, most soybean plants shed their leaves. An interested observer might notice that without a cover crop planted, a harvested soybean field appears quite bare in fall and over the winter.
Sometimes, farmers plant a winter wheat crop just after the soybeans are harvested, which then provides a cover for that field. During wheat harvest, there often are enough odd-shaped wheat kernels dropped that they "automatically" reseed the field, creating a near perfect cover crop through fall and winter.
In New York, our soil resources are quite different than other parts of the country. We have less top soil than places like the Midwest; therefore, farmers strive to do everything they can to keep it on their fields. One of these methods is planting cover crops. The cover crop helps stabilize the top soil layer by not exposing it to erosion by water or wind.
Cover crops also help “tie up” nutrients in their leaves and roots, keeping the nutrients from leaching or running off, thus protecting water quality. Cover crops work as a water filter system on fields, securing nutrients that will then be available for the next crop farmer's plant.
Cover crops can often out-compete weeds that are starting from seed already in the soil. The cover crop has a head start because it was planted earlier and will compete with germinating weed seeds for sunlight and space. Once the cover crop wins the competition, they shade out the weeds, resulting in fewer and less healthy weeds.
There are different species of cover crops, each serving different purposes. First is a winter cover crop that is planted in the late summer or fall to provide soil cover over the winter. Wheat is an example of a winter cover crop. A “catch crop” is a cover crop that is planted after harvesting the main crop, primarily to reduce nutrient leaching. Rye grass is often used as a catch crop. You may have heard the term "green manure"; this is when a green cover crop is incorporated into the soil to improve soil health by providing food for the soil’s natural flora and fauna called microorganisms. Cover crops can also serve as forage crops, meaning they are grazed or chopped, and fed to livestock.
Farmers strive to be good stewards of the land and water resources necessary to sustain their crops, livestock and families. Cover crops are one of several best-management practices used to help improve the productivity of crop fields. There is also the additional environmental benefit, which is why more acreage is planted to them each year as conditions allow.