Soil and water conservation and improved crop management programs were initiated in 1983 to increase the productivity of a dryland vertisol watershed in the state of Andhra Pradesh in the semi-arid tropical region of India. This was one of 47 model watersheds developed by the Government of India. The integrated program consisted of measures to conserve soil and water, such as a percolation tank, grading, checks, and deep tillage, on which were superimposed improved crop management practices (e.g., cultivars, fertilizers, and timeliness in operations), carried out with the farmers' cooperation and partial payment. All participants were surveyed in 1983, before starting the program, and 1988, after completing the program. The equilibrium water levels in open wells increased about 50 cm, which allowed sugarcane to be introduced. About 10% additional area was reclaimed and cultivated after construction of a diversion dam. Fodder supply improved because of the growth of natural grasses on terraces formed by stone checks in waterways. Soil and water conservation efforts reduced runoff about 26%. Ground cover increased by 38% because of increased cropping intensity, and income per capita grew by 67% per year. Thus, the integrated approach conserved natural resources and improved productivity.

The Northwest Wheat Region is a contiguous belt of 3.3 million ha in Idaho, Oregon and Washington. Its climate varies from subhumid (<650 mm annual precipitation) to semiarid (<350 mm), with more than 60% of the annual precipitation occurring during the winter. Winter wheat yields range from a high of 8 t/ha in the wetter zones to a low of 1.5 t/ha in the drier zones. Winter wheat is grown in rotation with spring cereals and pulses where annual precipitation exceeds 450 mm; winter wheat-fallow prevails where annual precipitation is less than 330 mm. Tillage practices are designed to maximize infiltration and retention of water through soil surface and crop residue management. Because of the combination of winter precipitation, steep topography, and winter wheat cropping, much of the region is subject to a severe water erosion hazard, accentuated by freeze-thaw cycles that increase surface runoff and weaken the soil structure. Wind erosion is a major problem in the drier zones, where cover is less and soils are higher in sand. Residue management, primarily through reduced tillage and no-till systems, is the first defense against both wind and water erosion, but yields often are higher with conventional intensive ti llage. Factors that limit yields with conservation farming include weed and disease problems and th e lack of suitable tillage and seeding equipment. Conservation strategies must shift from relying on traditional tillage methods to development of complete no-till systems. Spring cropping as a replacement for winter wheat also needs to be investigated. In some cases, tillage for water conservation must be made compatible with tillage for erosion control.

Little is known of how vertebrate pest and beneficial species respond to cover crops in vineyards and orchards. During spring 19941 interviewed 22 people who work with cover crops in California and searched for vertebrates and their signs in 36 field plots where cover crops were grown. Farmers usually relaxed concern for vertebrate pests after planting cover crops. But cover crops were thought to increase venebrate damage to trees and vines when planted continuously across the rows or grown in orchards and vineyards less than three years old. Vertebrates usually were not abundant or harmful to the commercial crops and cover crops I examined. Gophers were most abundant in older, uneven, scrappy, or weedy cover crops. They preferred beneficial and insectary blends and Cahaba white vetch, and were least abundant in grasses, subclover mixes, and bur medic. Voles preferred nontillage clover mixes, but avoided bare ground under vine and tree rows. All small mammals were more numerous near streams and recently tilled fields. Cover crops attracted many predatory vertebrates, which improve the aesthetic quality of the farm and might keep animal damage to economically acceptable levels. Cover crops can contribute to wildlife conservation in California, especially if the area in cover crops continues to increase.

Farm residues with high C:N ratios are difficult to use because of their low economic value and excessive volume. Composting is ideal for upgrading such residues, but was not thought possible without co-composting or lowering of the C:N ratio. We developed a low-input method to compost perennial ryegrass straw on-farm by forming windrows and turning them either zero, two, four, or six times throughout the year with a commercial, straddle-type turner. No water beyond normal rainfall and no N other than that contained in the straw was added. The volume of straw was reduced by up to 88% with four or six turns over 20 to 24 weeks. The average internal temperature of straw windrows reached a maximum of 54°C with four turns. The ability to compost these residues will help in the development of sustainable farming systems by allowing recycling of straw waste.

Sustainable crop production in the Pacific Northwest dry-farmed areas relies heavily on tillage and residue management systems to conserve water. Stable, sustainable yields cannot be achieved without adequate water conservation techniques. Frozen soil can reduce infiltration markedly, which decreases overwinter profile water storage and can cause severe soil erosion. Uncurbed evaporation losses throughout the year can greatly limit yields, particularly with summer fallow.

In both summer-fallowed and annually cropped regions where soil freezes frequently, fall tillage is used to increase surface macroporosity and to provide open channels to below the frost depth. This enhances infiltration throughout the winter and insures better water intake during rapid snowmelt and rainfall when the soil is frozen. Fall tillage enhances overwinter water recharge under these conditions, whereas in areas where soil freezes infrequently, it does not improve water storage efficiency.

In the dry-farmed regions receiving less than 330 mm annual precipitation, a winter wheat-fallow system is used to reduce the risk of uneconomical yields. Successful establishment of winter wheat following summer fallow is feasible only when proper management has suppressed evaporative loss. During the dry summer fallow, tillage is used to develop and maintain a soil mulch that restricts the flow of water, as both liquid and vapor. The tillage mulch effectively conserves stored soil water and maintains adequate seedzone moisture for fall establishment of winter wheat. However, the soil mulch can lead to high wind and water erosion.

In the Pacific Northwest dry-farmed region, tillage by itself is not considered a substitute for proper residue management. Crop residues following harvest are important for conserving water and controlling erosion. Under conservation programs implemented since 1985, shallow subsurface tillage systems that maintain residues on the surface have substantially reduced wind and water erosion in the region. Surface residues are effective in decreasing evaporative water loss and trapping snow during the winter, and therefore increase overwinter recharge. While surface residues are much less effective in suppressing evaporative losses in dry-farmed areas during extended dry periods, residues provide substantial control of wind and water erosion during the fallow.

Before conservation tillage systems came into use in the Pacific Northwest, water conservation frequently was achieved only through tillage. This helped to stabilize yields, but at a high cost to the soil resource. Poor use of surface residues and intensive tillage contributed to extensive wind and water erosion. Continued use of these practices would have caused yields to decline over time and required greater agrichemical inputs. To meet soil and water conservation needs, site-specific tillage and residue management systems were developed to account for the diversity and variability of soils and climate across the Pacific Northwest. Common to all these production systems is that both water conservation and effective residue management to protect the soil are required for long-term sustainable production.

Newly available data from USDA's Pesticide Data Program allow us to trace pesticide residues on fruits and vegetables to their sources among various uses. We show that pesticide residues come from four sources: on-farm pesticide use; post-harvest pesticide use; pesticide use on imported food; and canceled pesticides that persist in the environment. Post-harvest pesticides account for the largest share of residue detections. Farmers' pest control choices influence consumers' dietary intake of pesticides, but the way in which food is marketed and the history of pest management techniques used on farms may have a greater influence. For pesticides that U.S. farmers currently use, the data show the geographic sources of residues and the extent to which use contributes to dietary intake risks. This information could be used to target development of pest control alternatives more narrowly. However, research to develop on-farm pest control alternatives will not address all pesticide residue risks in consumers' diets.

This paper explores the constraints to sustainable agriculture in the Com Belt stemming from the trend toward increased farm size and the continued dependence of the region on undifferentiated farm commodities produced for regional, national, and international markets. It is based on a three-county comparison of 14 full-time farmers who have embraced sustainable principles and practices, and a randomly sampled group of 25 farmers. An encouraging finding was the substantial progress made towards lower-input production of com and soybeans by the nine farmers who had adopted the ridge tillage system, which uses elevated seedbeds, banded herbicides, and post-plant nitrogen application to reduce both soil erosion and synthetic chemical inputs while maintaining yields. However, operators of large farms that depend on hired labor and highly dispersed field sites regarded these practices as too risky at their scale of production despite their short-term economic and long-term environmental benefits. The region's commercial farmers appear split between family farmers who wish to avoid the headaches of scale expansion and hired labor, and therefore, embrace more efficient low-input systems such as ridge tillage versus those who reject the increased management intensity and risks of lower-input systems in favor of scale expansion via more chemical-intensive no-till systems. Although ridge tillage represents movement toward low-input cash grain production, low-input production systems alone are not sufficient to improve the underlying social welfare of rural areas. Arresting the trend towards fewer and larger farms will also require development of more specialized or more localized markets for sustainably produced commodities.

New crop production technologies developed in response to growing concern over environmental contamination from agriculture may be neither more profitable nor higher yielding than the systems they replace, but they often reduce environmental contamination or improve soil and water quality. Systems designed with environmental objectives cannot be evaluated fairly just by productivity, which is what often is done in economic studies of alternative systems. We review 58 recent studies comparing alternative crop production systems to identify the key criteria for system comparisons, the system characteristics important in designing the analysis, and the methods most suited for comparing alternative systems.

The four key criteria we looked for in system comparisons are expected profit, stability of profits, expected environmental impacts, and stability of environmental impacts. Most economic studies of crop production focus exclusively on profitability, and incorporate neither environmental criteria nor the dynamic characteristics inherent in alternative systems. We identify promising new approaches that take account of specific environmental characteristics and attempt to balance the objectives of profitability and environmental risk management. Balanced environmental-economic analysis is most likely to be achieved by integrating biophysical simulation models with economic optimization methods to model the trade-offs among profitability, environmental impact, and system stability (both financial and environmental).

With the passage of the 1990 Clean Air Act came the responsibility to monitor and control particulates in the size range 10 μ and smaller (PM10). Many urban areas, particularly in the western U.S., have experienced concentrations of fugitive dust particulates from upwind sources that exceed the federal health standards. Often a significant amount of this material is generated upwind on agricultural fields, and then is entrained and transported in the regional air mass, thus degrading the air quality in downwind urban regions. Current technology cannot adequately quantify the fugitive dust emitted and transported from agricultural sources, nor specify adequate control methods. A comprehensive research plan recently was developed and initia ted for the Columbia Plateau of eastern Washington State that involves multiple disciplines and several state and federal agencies. This research has several components: characterizing the soil, vegetation and climate in a region of 136,000 km2; developing wind erosion and fugitive dust emission relationships for individual farm fields; developing and applying transport-dispersion-deposition models of the region; selecting and testing farm-level control strategies; and providing public information to both the urban and farm communities for understanding the problem and developing management plans. Simultaneous receptor analyses and public health research combine to make this a comprehensive regional research effort on fugitive dust emissions and impacts.

In 1993, a breakthrough occurred for sales of organic food products in conventional supermarkets in Denmark. Since then, sales have increased markedly and consumers now have a choice between organic and conventional food products in nearly all supermarkets. This success owes much to the intense efforts of three main groups since the mid-1980s. First, organic farmers have increased production and successfully managed economic and organizational problems. Second, the Danish State has supported sales of organic products and farmers' conversion to organic farming by supporting marketing and product innovation and by organizing producers. Third, the largest Danish supermarket chain has contributed by its steady demand for organic products since 1981. Today, all major supermarkets in Denmark are supplied by conventional distributors that handle the products of small organic producer organizations. For nearly two years the system has kept up the positive effects of a market expansion process that was initiated by a major advertising campaign and a modest drop in consumer prices.

Disease resistance, increased crop residues and altered plant and canopy design are the primary strategies being used to solve the major problems of cool season food legumes that are an integral component of cropping systems in the rainfed areas of the U.S. Pacific Northwest. Dry pea, seed pea and lentil predominate among these legumes, but there is increasing interest in chickpea. Several diseases are major hazards to production, including root rots, wilts, powdery mildew, Ascochyta blight, and viruses. Pea and lentil cultivan resistant to root rots, wilts, and powdery mildew are being developed and released. Progress is being made on resistance to v iruses transmitted by aphids, including pea enation mosaic and bean leaf roll. Development of res istant cultivars has been the principal control strategy for several diseases: Ascochyta blight of chickpea and lentil; root rots and wilts of pea, lentil, and chickpea; powdery mildew of pea; and viruses of pea and lentil. Chickpea cultivars resistant to Ascochyta blight were recently made avallable to producers. Another problem is that crop residues are insufficient to control erosion. Research is underway on genetically increasing biomass and residue production in lentil and dry pea and on producing more lignified stems and other plant parts that are more resistant to breakdown during harvesting and subsequent tillage. Increased biomass also might increase grain yields and red uce harvesting losses. The semi-leafless and woody stem traits in pea, the bushy plant types of lentil and chickpea, and diverse pod traits in all the legumes have shown promise for increased yield potential, ease of harvest, and reduced shattering losses.

Anecic earthworms (e.g., nightcrawlers) create deep, vertical burrows and feed by dragging organic matter from the soil surface into the burrow, thereby incorporating organic matter. The incorporation of leaf litter in orchards may reduce inoculum levels of organisms that cause diseases such as apple scab. However, anecic earthworms are generally absent from agro-ecosystems in California, in part possibly because of low rainfall and seasonal drought. Anecic earthworms (Lumbricus terrestris) were introduced to an organic apple orchard in Watsonville, California, where the resident earthworm community included only the endogeic (subsurface-feeding) species Aporrectodea caliginosa and Microscolex dubius. With L. terrestris present, incorporation of apple leaf litter increased from less than 28% to 79%. Yearly patterns of activity of resident earthworm species were unimodal, corresponding to the winter season of peak rainfall and low soil temperature. Earthworm populations were similar for organic and conventional treatments until the third year, when abundance and biomass of resident species were significantly greater in the organic plots.