Cropping system

About: Cropping system is a research topic. Over the lifetime, 8049 publications have been published within this topic receiving 181326 citations.

Genetic diversity and disease control in rice

Abstract: Crop heterogeneity is a possible solution to the vulnerability of monocultured crops to disease1,2,3. Both theory4 and observation2,3 indicate that genetic heterogeneity provides greater disease suppression when used over large areas, though experimental data are lacking. Here we report a unique cooperation among farmers, researchers and extension personnel in Yunnan Province, China—genetically diversified rice crops were planted in all the rice fields in five townships in 1998 and ten townships in 1999. Control plots of monocultured crops allowed us to calculate the effect of diversity on the severity of rice blast, the major disease of rice5. Disease-susceptible rice varieties planted in mixtures with resistant varieties had 89% greater yield and blast was 94% less severe than when they were grown in monoculture. The experiment was so successful that fungicidal sprays were no longer applied by the end of the two-year programme. Our results support the view that intraspecific crop diversification provides an ecological approach to disease control that can be highly effective over a large area and contribute to the sustainability of crop production.

Nitrogen in Agriculture: Balancing the Cost of an Essential Resource

Abstract: Nitrogen (N) is central to living systems, and its addition to agricultural cropping systems is an essential facet of modern crop management and one of the major reasons that crop production has kept pace with human population growth. The benefits of N added to cropping systems come, however, at well-documented environmental costs: Increased coastal hypoxia, atmospheric nitrous oxide (N2O), reactive N gases in the troposphere, and N deposition onto forests and other natural areas are some of the consequences of our inability to keep fertilizer N from leaving cropped ecosystems via unmanaged pathways. The N cycle is complex, and solutions require a thorough understanding of both the biogeochemical pathways of N in agricultural systems and the consequences of different management practices. Despite the complexity of this challenge, however, a number of technologies are available today to reduce N loss. These include adding rotational complexity to cropping systems to improve N capture by crops, providing farmers with decision support tools for better predicting crop fertilizer N requirements, improving methods for optimizing fertilizer timing and placement, and developing watershed-level strategies to recapture N lost from fields. Solutions to the problem of agricultural N loss will require a portfolio approach in which different technologies are used in different combinations to address site-specific challenges. Solutions will also require incentives that promote their adoption.

Evaluating Cover Crops for Benefits, Costs and Performance within Cropping System Niches

Abstract: The integration of cover crops into cropping systems brings costs and benefits, both internal and external to the farm. Benefits include promoting pest-suppression, soil and water quality, nutrient cycling efficiency, and cash crop productivity. Costs of adopting cover crops include increased direct costs, potentially reduced income if cover crops interfere with other attractive crops, slow soil warming, difficulties in predicting N mineralization, and production expenses. Cover crop benefits tend to be higher in irrigated systems. The literature is reviewed here along with Michigan farmer experience to evaluate promising cover crop species for four niches: Northern winter (USDA Hardiness Zones 5-6), Northern summer (Zones 5-6), Southern winter (Zones 7-8), and Southern summer (Zones 7-8). Warm season C 4 grasses are outstanding performers for summer niches (6-9 Mg ha -1 ), and rye (Secale cereale L.) is the most promising for winter niches (0.8-6 Mg ha -1 ) across all hardiness zones reviewed. Legume-cereal mixtures such as sudangrass (Sorghum sudanese L.)-cowpea (Vigna unguiculata L.) and wheat (Triticum aestivum L.)-red clover (Trifolium pretense L.) are the most effective means to produce substantial amounts (28 Mg ha -1 ) of mixed quality residues. Legume covers are slow growers and expensive to establish. At the same time, legumes fix N, produce high quality but limited amounts (0.5-4 Mg ha -1 ) of residues, and enhance beneficial insect habitat. Brassica species produce glucosinolate-containing residues (2-6 Mg ha -1 ) and suppress plant-parasitic nematodes and soil-borne disease. Legume cover crops are the most reliable means to enhance cash crop yields compared with fallows or other cover crop species. However, farmer goals and circumstances must be considered. If soil pests are a major yield limiting factor in cash crop production, then use of brassica cover crops should be considered. Cereal cover crops produce the largest amount of biomass and should be considered when the goal is to rapidly build soil organic matter. Legume-cereal or brassica-cereal mixtures show promise over a wide range of niches.