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.

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.

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.

Interest in developing more sustainable cropping systems has led to renewed interest in legumes as N sources for crops. We conducted a 2-year study to compare the effects of green manure, green manure plus fertilizer, and fertilizer on wheat yield and N leaching potential. In 1991–92, wheat following corn and receiving 0, 45, or 90 kg N/ha was compared with wheat planted after plowing the autumn regrowth of red clover/johnsongrass hay (supplemented with alfalfa) that supplied 107 kg total N/ha. In 1992–93, wheat following corn and receiving 90 kg N/ha was compared with wheat following hay regrowth that either received fertilizer N at 45 kg/ha or 90 kg N/ha or was supplemented with alfalfa (total of 123 kg N/ha). Yield with only green manure averaged 65% of yield with 90 kg N/ha. Yields with green manure plus 45 or 90 kg N/ha were not different from yield with 90 kg N only. The first year, soil to a depth of 30 cm declined from as high as 40 kg/ha in the fall to less than 10 kg/ha as wheat growth increased in the spring. In contrast, concentration averaged 20 kg/ha throughout the growing season. Trends in soil inorganic N were similar the second year. Profile nitrate distribution indicated a greater potential for N leaching with fertilizer than with green manure. Soil from the site was used in a laboratory incubation study to determine the rate of N mineralization from white clover at 10°C. An average of 80% of the clover N was recovered as soil inorganic N; however, in the field study, recovery (soil inorganic N in the 0 to 30-cm zone + Nin above-ground wheat biomass) was only 21%. Supplementing green manures with spring applications of fertilizer N could decrease the leaching loss without decreasing wheat yield.