A 9-yr large-scale integrated pest management (IPM) study was initiated in 1985 to develop and refine profitable conservation cropping systems in the Palouse wheat-growing region of the Pacific Northwest. Weed scientists from the USDA-ARS and the land-grant universities of ID and WA led a team of researchers and extension personnel from eight disciplines to investigate the interactions of crop systems, tillage systems, and weed management levels (WML) on crop production. Ineffective weed control has been a major deterrent to the adoption of conservation tillage by wheat growers. With this in mind, the primary focus of the scientists on the IPM project was integrated weed management (IWM) in conservation crop production systems for highly erodible land. For the first time in the Pacific Northwest, systems research developed a conservation production system using a 3-yr crop rotation that controlled weeds effectively, reduced erosion, was less risky than traditional farming systems, and was profitable. Broadleaf weeds were more prevalent in the 3-yr rotation of winter wheat-spring barley-spring pea compared to continuous wheat in both conservation and conventional tillage systems. In conservation tillage, troublesome grass weeds included wild oat and downy brome. Wild oat was controlled effectively at the moderate and maximum weed management levels under conservation tillage in the 3-yr rotation. Two years out of winter wheat (such as in the 3-yr rotation) reduced downy brome populations. In contrast, growing a spring crop 1 yr, followed by 2 yr of winter wheat was not effective for controlling downy brome. Effective weed control was instrumental in developing successful conservation IPM cropping systems, and education and technology transfer were important in helping action agencies assist growers in adopting these systems.

Six papers in this issue were presented by Middle Eastern authors at the U.S.-Middle East Conference and Workshop on "Dryland Farming Systems and Technologies for a More Sustainable Agriculture," held at Moscow, Idaho on October 18–23, 1993.

A 6-yr interdisciplinary field project using large plots was initiated in 1985 to assist Pacific Northwest growers in developing an integrated pest management system to control weeds, reduce erosion and grow crops profitably. Run by a network of 10 to 14 scientists from eight disciplines supported by five agencies, the project showed that wellmanaged conservation tillage systems had a higher average profit and lower economic risk than traditional conventionally tilled systems. Information was disseminated successfully to user groups by field days, plot tours and an educational video. Organizational strategies included an interdisciplinary design with three levels of objectives. Cooperating scientists were invited to participate in writing the proposal and followed strict field protocols and attended mandatory organizational meetings. This long-term study used large machinery, went beyond the transitional stage and allowed treatments to mature. Limitations included the restricted number of experimental variables, the location of the plots, the large labor force required, and publication decisions.

Soil is the world's most vital component for food and fiber production: preservation of this critical natural resource is paramount for protecting the environment, and ensuring that current and future populations are healthy and well-fed. In many countries of the world, including the United States, soils are being degraded at an alarming rate by wind and water erosion, desertification, and salinization resulting from misuse and improper farming practices. Often the topsoil is lost at a rate that far exceeds the capacity of natural processes to regenerate it. With soil degradation, there is a concomitant decline in soil quality, i.e., the soil's capacity to produce healthy and nutritious crops, resist erosion, and reduce the impact of environmental stresses on plants. Many decades of research have consistently shown that the best means of improving and restoring soil quality and productivity is by proper and regular additions of organic materials mainly through the use of crop rotations, cover crops, crop residues, animal manures, composts, and reduced tillage.

Evidence indicates a strong positive relationship between increases in nitrogen fertilizer use on cropland and nitrate concentrations in shallow ground water. This raises concern about the fate and efficiency of nitrogen fertilizer with current farming practices. Approximately 50 percent of the nitrogen fertilizer applied may be recovered by agronomic crops and 35 percent or less removed in the harvested grain of a crop such as corn. The residual nitrogen is subject to loss by several processes, one being leaching from the crop root zone. Alternative production systems that provide ground water protection must give attention to improved management of nitrogen fertilizer and to practices that minimize the need for nitrogen fertilizer and reduce soil nitrate concentrations. Most important in nitrogen fertilizer management is to more closely match nitrogen availability in the soil with crop needs and to avoid over-fertilization. Nitrogen fertilizer use can be reduced by alternate cropping of low and high nitrogen-demanding crops, use of legumes in the crop rotation to fix nitrogen, and proper use of manures, crop residues, and other organic wastes. Residual nitrates in soil can be reduced by use of cover crops, nitrogen-scavenging crops in the rotation, and alternating shallow and deep-rooted crops. Conservation tillage alone as used with many conventional cropping systems will probably not change the current status of nitrate leaching. Practices used by organic farmers should be carefully studied as possible approaches for ground water protection and adaptation into conservation tillage systems for conserving soil and water resources.

Modern large-scale conventional agriculture with intensive monoculture and row-cropping practices often results in unacceptable soil erosion and runoff and in associated losses of nutrients and pesticides. It also adversely affects wildlife. Sediment from erosion is the greatest pollutant of surface water in the United States and is a major carrier of agrichemicals into the water system. Conservation tillage practices can significantly reduce soil losses in modern production systems, but pollution of surface and groundwaters from runoff and associated potential for increased use of pesticides may still present a hazard. Erosion can be reduced to tolerable levels by the use of crop rotations, meadow crops, and mulch tillage, as commonly used in alternative agriculture. These cultural practices also result in diversity in crop types and in smaller fields, with possible benefit to many wildlife species. Chemical threats to the environment and to wildlife are reduced because synthetic chemicals are used sparingly or not at all.