The purpose of this paper was to quantify economic and energy use implications of new improved irrigation and limited tillage production systems for the Texas High Plains. Per hectare uses of natural gas and electricity under alternative irrigation distribution systems for corn, sorghum, wheat, cotton, and soybeans were utilized to estimate total amounts of natural gas and electricity used in the production of these crops on the High Plains of Texas. The amount of diesel fuel used was estimated for conventional and limited tillage systems under dryland and irrigation production. Total amounts of water used for the five crops under the improved and conventional irrigation systems were also estimated for the High Plains. Results indicated improved irrigation and limited tillage systems reduced energy and water use on the High Plains. Total natural gas and electricity were estimated to decline over 20 percent, diesel fuel declined 32 percent, and water use for irrigation declined about 23 percent. Use of the improved irrigation and limited tillage production systems was also shown to significantly increase annual net returns to farmers ($40.0 million or 13.3 percent).

Contamination of ground water from agricultural sources has been documented in a majority of the contiguous United States. In this study, we examine the potential for voluntary adoption of management practices that reduce risk of ground water contamination and discuss how f arm operators' attitudes regarding the environment might affect the success of voluntary programs. Farmers' behavior and attitudes in Rockingham County, Virginia, and Big Spring Basin, Iowa, reveal that both groups consider the ground water issue to be a serious problem to which they are contributing. This awareness is a significant first step in prompting consideration of management practices that reduce the threat to ground water quality. We also found that the “worst offenders”—that is, farmers applying nitrogen well above agronomic recommendations-were those with the least concern about the problem. If major shifts in farming practices are to occur voluntarily, major incentives or disincentives are needed. Even though the concern about ground water quality is high, the documented risks perceived by farmers are not strongly convincing. The economic incentives for change are questionable at best. Voluntary adoption of best management practices is only one of several policy options. Ultimately, policies designed to reduce ground water contamination may need a mix of strategies, including economic incentives and disincentives, zoning and land use restrictions, environmental regulations, and bans on agricultural chemicals.

In the fifth year of an agricultural conversion experiment in Pennsylvania, we studied the soil biological community under three treatment regimes planted with corn: organic-manure, organic-legume, and a conventional system. The organic treatments consisted of complex crop rotations, cultivations, and organic matter inputs to control pests and maintain soil fertility. The conventional system consisted of a simple corn/soybean rotation with synthetic fertilizer and pesticide inputs. High rates of CO2 evolution (a measure of potential microbial activity) in the organic plots corresponded with high levels of organic matter input. Soil nematodes were most abundant in organic plots, although seasonal patterns differed between the two organic treatments. Soil microarthropods were dominated by fungivorous Prostigmata mites, which reached peak abundance in organic plots two to five months after organic matter incorporation. Oribatid mites, which were rare throughout the study, followed the same pattern of abundance in each treatment and were probably most influenced by tillage disturbances. Predatory Mesostigmata were generally more abundant in organic plots. Surface-dwelling Collembola were abundant briefly in the spring, but soil-dwelling species dominated numerically throughout the cropping season. Spring tillage appeared to have a strong negative effect on earthworm populations in all plots. Small earthworm species became abundant in organic-manure plots during the summer. Larger earthworm species were abundant in organic-legume and conventional plots after the autumn harvest, when crop residues covered the undisturbed soil The systems-level nature of the Conversion Project experiment makes it difficult to identify cause-effect relationships. The data do suggest that organic amendments tend to enhance soil biological activity, while tillage disturbances tend to disrupt the biotic community.

The development of political strategies in Canada to support the transition from conventional to sustainable agriculture has been limited by the absence of a comprehensive conceptual framework for identifying the most critical policies, programs, and regulations. In this paper, we propose a framework that uses an efficiency/substitution/redesign spectrum to categorize both sustainable fanning systems and government activities. The framework is then used to identify a diverse range of short, medium, and longterm strategies to be pursued by governments in Canada to support the transition. Strategies discussed include research, diffusion, and training; market development; and safety net programs and tax provisions. Finally, the implications and implementation of the redesign concept for food production, processing, and distribution are outlined.

Afield study was conducted between 1972 and 1982 to compare the effects of previous crop on row crop yields under rainfed conditions in eastern Nebraska. The objectives were to determine the effects of fallow and three previous crops: corn (Lea. maysLJ, soybeans /Glycine max (L.) Mem], and grain sorghum /Sorghum bicolor (L.) Moench], on the growth and grain yield of the same crops. The study was conducted on a Sharpsburg silty clay loam (fine, montmorillonitic, mesicf Typic Argiudoll). Corn grain yield was most variable (C. V. 23.4percent) compared to soybean (C. V. 13.6percent) or grain sorghum (C. V. 9.5 percent) yields. Corn was also the most sensitive crop to previous crop effects. The range of treatment yields for each crop was 47 percent, 22 percent, and 11 percent of the overall means for corn, soybean, and sorghum, respectively. Previous crop affected yields for all crops, but the effects were not consistent across years. All crops produced highest yield following fallow. Yields of corn, soybean, and grain sorghum following fallow were 74, 25, and 10 percent higher than their respective monoculture yields. In years of average precipitation, a corn-soybean sequence produced the greatest yield. In years having above- or below-normal precipitation, a grain sorghum-soybean sequence produced the highest yield.

Practical Farmers of Iowa is a grassroots organization whose members conduct research on profitable, environmentally sound alternative production methods on their own farms. The experimental design uses randomized, replicated side-by-side machine-harvested strips running the length of the field. Production techniques investigated include ridge tillage with and without herbicides, ridge tillage and conventional tillage without herbicides, with cover crops, and with late spring soil nitrate tests to determine efficient N application rates. This work has led to effective cooperation among farmers, extension personnel, and university researchers, and has inspired similar activities in other states.

Recent research and debate in sustainable agriculture has focused on the role of commodity programs in shaping rotation decisions. The commodity programs are often cited as obstacles to establishing long-term, diversified rotations. However, predicting which rotations would be practiced in the absence of commodity programs is difficult. How strongly commodity programs influence the rotation decision depends on the size of the economic incentive to participate and the percentage of cropland enrolled in the program. Data from the Agricultural Stabilization and Conservation Service (ASCS) were used to calculate the distribution of the percentage of cropland in corn base for each farm record at ASCS in the Corn Belt and Lake States in 1988. The distribution shows that the level of corn program enrollment varies widely. Many corn base acres are found on farms with high corn base enrollment levels, which potentially constrains the rotation choice. However, enrollment levels in the corn program do appear to allow the option of diversified rotations for many corn base acres in the Corn Belt and Lake States, even during the high corn price support years of the mid to late 1980s.

Impediments to agricultural change extend beyond lack of appropriate research and the federal farm program to addiction to use of agricultural chemicals. Several recent trends in American agriculture have been caused by or have resulted in dependence on agricultural chemicals. They include the continuing separation of livestock from farms, farm size, separation of ownership and farming of the land, discontinuity of learned procedures, part-time farming, and certain aspects of noxious perennial weeds. This implies that prospects for agricultural change are related to the trends with which they are associated.

Phosphorus (P) accumulation and use efficiency by broccoli (Brassica oleraceae var. italica) were observed in a field plot study comparing management with varying levels of conventional fertilizer, differing composted amendments, and a combination of inorganic Nitrogen (N) and compost sources. Total P accumulation and yield were highest in treatments incorporating solely compost or vermicompost applications of 30 tons ha–1. Applications of N as ammonium sulfate caused significant soil acidification, which lowered yield and P uptake. Poor growth and yield were probably related to manganese toxicity effects on root extension and activity. These effects were partly ameliorated in treatments combining fertilizer N and compost sources. As a result, yield in plots receiving 75 kg N ha–1 as ammonium sulfate and 8.9 kg P ha–1 as compost was nearly identical to highest experimental yields. Phosphorus use efficiency was highest in this treatment incorporating fertilizer N and compost. Generally, P use efficiency tended to decline at the highest levels of fertilization. We propose that intensive organic matter management may be a good way to improve P use efficiency by vegetable crops.

Farmers and the agricultural research and extension community at the land grant universities have experienced an evolving relationship. The current call for reform in publicly sponsored agricultural research and extension is built upon more than a century of dialog. If specialization and discipline-oriented research is to continue, the ecosystem-based knowledge of the farmer will become increasingly valuable. Involving farmers more actively in research and education could be achieved in several ways. Outside the land grant system, nonprofit agricultural research and demonstration organizations are being developed. Within the public system we need a renewed emphasis on extension at the local level and a revitalized applied research effort aimed at solving problems of the agricultural ecosystem rather than single disciplines. A dynamic and resourceful agriculture could result from including the farmer as a full partner in land grant research and education.