BOX 9-1

Examples of Practices That Contribute to Sustainability

Production Practices

  • Conservation (or reduced) tillage systems have become common for many crops and soil types. As of 2004, 41 percent of planted crop acreage was managed with conservation tillage. Water-caused soil erosion and surface runoff of nutrients, chemicals, and crop residues have been greatly reduced. Although no-till leads to savings on fossil fuel and labor, it could result in lower yields and greater difficulty with weed control than conventional till. Thus, the economic effect of no-till versus conventional till is unclear.

  • Cover cropping provides ground cover to protect soil. Cover crops can also be used to provide other services, including maintenance of soil organic matter and provision of nutrients to subsequent crops (green manures), trapping excess nutrients in the soil profile following harvest of the primary crop, and preventing leaching losses (catch crops). However, cover crops are not widely planted because they require complex management skills and their seeding costs could be high.

  • Crop diversity, including rotations, intercropping, and using different genetic varieties can contribute to improving soil quality, enhancing ecosystem function, and managing pests and diseases. Although the use of diverse cropping systems has increased, it fluctuates widely with commodity prices. Diverse cropping systems require extensive knowledge and management skills to identify the right combination of crops to achieve multiple sustainability goals. Comparative economic studies reported economic advantages for diversified rotation in some cases and disadvantages in others. The variation in results is partly attributable to market and policy conditions.

  • Traditional plant breeding and modern genetic engineering techniques will continue to be used to develop crop varieties with increased yields, pest and disease resistance, enhanced water-use and nutrient-use efficiencies, and other important traits. Genetic engineering (GE) has the potential to contribute novel solutions for problems that could not be addressed with natural plant genetic resources or traditional plant breeding methods. New GE varieties would have to be tested rigorously and monitored carefully by objective third parties to ensure environmental, economic, and social acceptability and sustainability before release for planting.

  • Many technologies for efficient water use such as metering, improved distribution of high-pressure water, and low-pressure, directed-use systems offer promise to address water scarcity. Water reuse is another strategy for addressing water scarcity, but the biological and chemical quality of the reclaimed water would have to be monitored carefully.

  • Best management practices (BMPs), including nutrient management planning, field buffer strips, riparian area management, surface and subsurface drainage water management, and livestock manure management, have been developed to mitigate the runoff of agricultural nutrients and chemicals into the nation’s surface and ground waters. Effectiveness of BMPs at the watershed scale has been difficult to prove, in part because actions by individual farms might not be visible at the landscape scale. The benefits of BMPs can vary widely depending on characteristics of the landscape, weather events, and time lags between BMP adoption and physical changes in the dynamics of nutrient and chemical cycling on farm fields.

social aspects of the many current and potential technologies and management practices and that addresses issues of resilience and vulnerability in biophysical and socioeconomic terms.

TRANSFORMATIVE APPROACH TO IMPROVING U.S. AGRICULTURAL SUSTAINABILITY

If major farming systems and aggregations of systems within key production regions have gradually evolved toward meeting some sustainability goals while moving toward unacceptable ends of the others, as indicated by scientific knowledge accumulated over



The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement