Cover crops Cover crops are used to minimize the effects of the main crop. They provide a protective cover that reduces the risk of runoff and erosion between two growing seasons. There are two main types of cover crop. Intercrops are grown along with the major crop. For example, a forage crop can be seeded between corn rows or spring wheat underseeded with red clover.
Green manures are crops that are generally sown after the main crop has been harvested.
Cover crops also act as a sink for nutrients remaining in soils, preventing their loss by runoff or leaching. This function is particularly important with respect to nitrogen. Plowing under these crops or spraying them with herbicide in the late fall or early spring increases the availability of the nutrients to the following crops. Other benefits of cover crops include weed control maintenance of organic matter nitrogen fixation when legumes are used reduced wind erosion and damage to young plants. Among the drawbacks of cover crops are that they compete with the main crop for water and nutrients and add to production costs.