REDUCING NITRATE LOSSES FROM AGRICULTURAL FIELDS WITH SUBSURFACE DRAINAGE
Title: The use of cover crops to manage soil
Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: December 6, 2010
Publication Date: May 23, 2011
Citation: Kaspar, T.C., Singer, J.W. 2011. The use of cover crops to manage soil. In: Hatfield, J.L., Sauer, T.J., editors. Soil Management: Building a stable base for agriculture. Madison, WI: American Society of Agronomy and Soil Science Society of America. p. 321-337.
Interpretive Summary: Inserting cover crops into fallow periods and spaces in cropping systems is a beneficial soil management practice. Cover crops can protect the soil from erosion, reduce losses of nitrogen (N) and phorphorus (P), increase soil carbon (C), reduce runoff, inhibit pests, and support beneficial soil fauna. Although cover crops have the potential to maintain and enhance soil productivity and to reduce offsite impacts of N, P, sediment, and greenhouse gases, they are not widely used in most agricultural systems. Incorporating cover crops into cropping systems requires time, money, inputs, machinery, labor, and modifications of current practices without immediate financial return to the farmer. Improvements in soil productivity resulting from cover crops may require many years before benefits are detectable. Additionally, availability of cover crop management information, cover crop seed, and custom planting and spraying services need to be improved to facilitate adoption of cover crops in grain, oilseed, and fiber cropping systems. However, if farmers are given financial and productivity incentives to grow cover crops, farmers, crop consultants, and scientists should be able to overcome these management, supply, and service problems relatively quickly. Therefore, scientists need to demonstrate to farmers with long-term integrated studies that maintaining or enhancing soil productivity with cover crops provides long-term financial benefits. Additionally, scientists need to demonstrate to non-farmers that providing incentives for widespread adoption of cover crops could provide valuable ecosystem services and improvement of water quality, while still maintaining current levels of food, biomass, and fiber production. The impact of this literature review is to provide literature-based information to agricultural professionals about the beneficial soil management roles of cover crops.
Cover crops are used to manage soils for many different reasons. Inserting cover crops into fallow periods and spaces in cropping systems is a beneficial soil management practice. Natural ecosystems typically have some plants growing, covering the soil, transpiring water, taking up nutrients, fixing carbon, and supporting soil fauna for most of the time that the ground is not frozen. Agricultural cropping systems producing grain, oilseed, and fiber crops in temperate regions typically only have living plants for four to six months of the year and are fallow for the remaining six to eight months. Current planting and tilling practices often leave soil bare and exposed during fall, winter, and early spring. Some perennial cropping systems for nut or fruit crops keep the spaces between rows fallow and tilled for extended periods. As a result of these fallow periods and spaces in annual and perennial cropping systems, soil is left unprotected from erosive forces, nutrients and organic matter are lost or not replenished, runoff increases, soil fauna are stressed, and soil productivity diminishes. Thus, inserting cover crops into fallow periods or spaces in cropping systems can accomplish multiple soil management goals. This discussion is not intended to be a comprehensive review and will focus on the general principles and evidence for using cover crops to manage soil erosion, runoff, soil nutrients, soil water, soil organic matter, soil physical properties, soil chemical properties, and soil biology.