Submitted to: Encyclopedia of Soil Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/22/2016
Publication Date: 9/15/2016
Citation: Delgado, J.A. 2016. Cover Crops. Encyclopedia of Soil Science. Third Edition. CRC Press. doi:10.1081/E-ESS3-120054071.
Interpretive Summary: Cover crops (CC) are key soil and water conservation tools that can be used across a large number of worldwide agroecosystems to protect soil and water quality. The benefits of cover crops are very extensive. Cover crops can be used to provide a large number of ecosystem services. They are tools that can be used for different objectives to provide positive agricultural and environmental impacts. A typical use of cover crops is their use to maintain the soil surface cover to reduce soil erosion potential from wind and/or water. Cover crops can be used to reduce the off-site transport of soil particles, nutrients, organic matter, and agrochemicals. This makes cover crops key tools for maintaining and/or improving soil quality and soil health. Cover crops are also excellent tools for nutrient management. They can help scavenge residual soil nitrate, reduce nitrate leaching, and even mine nitrate from groundwater, helping to reclaim and clean groundwater. Cover crops can be used to increase cropping system nitrogen use efficiency to protect water quality. Cover crops can also contribute to increased populations of beneficial insects, weed management and suppression, and pest management. By serving as biocontrol tools, cover crops can contribute to decreased use of agrochemicals and protect water and environmental quality. Summer cover crops with limited irrigation can potentially be used to increase yields, crop quality, and nutrient and water use efficiencies while protecting the environment. Similarly, winter cover crops can also contribute to protection of the environment by reducing the transport of nutrient off-site, and for some cropping systems, they can contribute to increased yields and nutrient use efficiencies.
Technical Abstract: Cover crops are great tools to improve soil quality and health, and great tools to increase carbon sequestration. They are nutrient management tools that can help scavenge nitrate, cycle nitrogen to the following crop, mine NO3 from groundwater, and increase nitrogen use efficiency of cropping systems. Nitrogen cycling from cover crops is more efficient than from inorganic N fertilizer, and cover crops act like a slow-release fertilizer, with 66% lower losses than the losses from inorganic N fertilizer.Cover crops can be grazed or harvested for hay, used as a mulch, or incorporated as green manures. Cover crops can contribute to suppression of weeds and pests. Cover crops are excellent tools for soil and water conservation and climate change adaptation and mitigation. In general, the benefits of cover crops are so numerous that nutrient managers, conservation practitioners, and others use them as tools to increase nutrient use efficiencies; reduce off-site transport of soil particles, nutrients and agrochemicals; recover soil NO3-N from the soil profile and cycle to the next crop; improve soil, air, and water quality; and reduce pests and weeds. Improving yields is one reason cover crops are a key soil and water conservation practice. Fortunately, for the majority of cropping systems, management can potentially be used to minimize the negative impacts of cover crops on yields by using the right cover crop for the right crop situation for a given combination of soil, weather, and cropping system. Cover crop management is essential to provide all the benefits of cover crops while maintaining and/or increasing yields of the subsequent crop.