Submitted to: Haworth Press
Publication Type: Book / Chapter
Publication Acceptance Date: 12/17/2005
Publication Date: 3/27/2006
Citation: Sainju, U.M. 2006. Cover crops for sustaining vegetable production, improving soil and water qualities, and controlling weeds and pests. In: R Dris, editor, Vegetables: Growing Environment and Mineral Nutrition. Binghamton, New York: Hawthorn Press, Inc. p. 281-296.
Interpretive Summary: Cover crops, grown to cover exposed soil for reducing soil erosion, play important roles in sustainable crop production. They influence on crop yields, soil and water qualities, and incidence of weeds, pests, and diseases. While no fertilizers, herbicides, or pesticides are used to grow cover crops, they use residual nutrients, such as N, P, K, left in the soil after main crop harvest, thereby reducing the potentials of nutrient loss through erosion and leaching. When cover crop residues are incorporated into the soil, the increased biomass produced by cover crops compared with weeds in the bare soil not only recycle residual nutrients but also improve soil quality by increasing organic matter concentration, thereby improving the physical, chemical, and biological properties of the soil. While nonlegume cover crops are effective in removing soil residual N and reducing N leaching, legume cover crops are effective in supplying N to the summer crops, increasing their yields, and reducing the rate of N fertilization. Abundant information is available about the effects of legume and nonlegume cover crops on the growth and yield of cereal crops. Relatively, little is known about their effects on vegetable production. Vegetable production differs from cereal production in management intensity and amount of inputs required. While cereals crops are intensively managed mostly during planting and harvesting seasons, vegetables require greater degree of management throughout their growth. This is because vegetables grow and mature rapidly and compete intensively with weeds. Furthermore, pest and disease incidences are more likely to occur in vegetables than in cereals. As a result, cultural practices, such as weeding and applications of herbicides, pesticides, or irrigation, need to be carried out more frequently throughout the vegetable growing season. Furthermore, fertilizers, such as N, needs to be applied more frequently than in cereals for obtaining optimum yields. This is because nutrient uptake and recovery is lower in vegetables than in cereals, and most of nutrients in vegetables are used for the production of fruits, tubers, or bulbs. Because of the rapid mineralization of cover crop residues in the soil, cover crops have improved soil properties and increased vegetable yields, especially in tomatoes (Lycopersicum esculentum Mill.), eggplants (Solanum melogena L.), and bell peppers (Capsicum annuum L.), similar to those did by N fertilization. The paper discusses recent advances on the effects of cover crops on vegetable production, soil and water qualities, and control of weeds, pests, and diseases. It also emphasizes on the economic evaluation about the cost of growing cover crops and their benefits about sustained vegetable production, reduced rate of N fertilization, reduced soil erosion, improved soil and water qualities, and reduced incidences of weeds, pests, and diseases. Growers will find useful information about growing cover crops in vegetable production system.
Technical Abstract: Cover crops are usually grown after the harvest of main crops to cover soil and reduce erosion. Besides sustaining crop yields, cover crops have many benefits in improving soil and environmental qualities. They use residual soil N and reduce N leaching in the groundwater. They increase soil organic matter and improve soil physical, chemical, and biological properties. Legume cover crops fix N from the atmosphere, supply N to the succeeding crops, and reduce the rate and cost of N fertilization. As a result, they increase crop yields compared with nonlegume or no cover crops. They control many weeds, pests, and diseases. Cover crops also sequester atmospheric C and N in the plant biomass and soil and help to reduce global warming. However, some of disadvantages associated with cover crops include cost of seeding and their growth restriction on places with cold winter. Cover crops need to be economically evaluated for their benefits on vegetable production and soil and water qualities versus their cost of seeding that are socially acceptable to the producers.