Chemical fertilizers are used only in a limited way under dry farming conditions in India because of their high cost and the risk of crop failures due to drought Several alternative strategies are being evaluated to reduce the cost of supplying N to castor bean without adversely affecting yield. We report the results of a two-year study on the possible replacement of fertilizer nitrogen by green leaves from Leucaena leucocephala for production of castor beans on a low fertility Alfisol Bean yield and dry matter production were significantly higher when 50 kg N/ha was applied as green leaves compared with 50 kg N/ha as urea. Among substitution levels, 37.5 kg N/ha as green leaves at planting followed by 12.5 kg N/ha as urea at 45 days after planting was found to be the most effective combination. Across all the substitution levels, addition of nitrogen as green leaves at planting was found to be better than application at 45 days after planting. Nutrient and water use efficiencies were higher when the N was applied as green leaves compared to urea. Nitrogen use efficiency was higher for green leaves than for urea under limited rainfall conditions. The overall data indicated that 75 percent of the fertilizer N requirement of castor bean can be supplied by leaves of Leucaena leucocephala when applied at planting.

We surveyed shoppers at a food cooperative in New York state to measure the relationship between organic produce purchases and attitudes related to pesticide use in agriculture, food costs, and other factors affecting produce buying. Two-fifths of the co-op shoppers surveyed usually or almost always purchased organically grown produce, and one-third were somewhat or very likely to pay 100 percent more than conventional produce for residue-free produce. Those who usually or almost always purchased organic produce were less concerned than other shoppers about price when they shop for produce, had higher levels of concern about food safety, and were less concerned about insects and surface blemishes on produce. There was no relationship between income and frequency of organic purchases. Most shoppers were concerned about pesticide residues in produce, but a high level of concern appeared necessary to affect the frequency of organic purchases. In their support of organic agriculture, respondents ranked environmental protection higher than consumer protection. Educators should emphasize both the environmental and food safety benefits of organic farming to consumers.

Water harvesting technologies capture surface water runoff and recycle it for productive use. Despite the long history of water harvesting and the renewed interest in many places in the world, the technology has not been widely adopted in the United States, in part because of a lack of understanding of its economic benefits. We developed a simulation model for the economic evaluation of water harvesting systems that combines agronomic, engineering, and economic factors and daily meteorological data. The simulation model was used to investigate the economic feasibility of using a water-harvesting, supplemental irrigation system for grain sorghum production over a 44-year period at two locations in Texas. Water harvesting combined with supplemental irrigation was most successful where the precipitation is the highest. However, the net benefits were extremely variable from year to year. The modeled technique could not take advantage of the potential additional water in the wet years and did not harvest sufficient water in dry years to make water harvesting more economically attractive than conventional dryland farming. This does not mean that runoff farming cannot be of economic benefit, depending on local conditions. Widespread adoption of the technology is constrained by the limited profit potential the variability of the profits, and the knowledge required to use the technology successfully. The simulation model was a useful and simple tool for dealing with the complexity of the issues.

Systems that reduce the use of fertilizers and pesticides are commonly said to do so by greater use of information and ecological understanding. However, this plausible proposition has not received much empirical examination. Different possible roles of information have not been clearly differentiated: in the development of new methods, in the farmer's decision whether to adopt them, and in their continued use. Also, the additional work that might be needed to handle information in reducedchemical systems often is not distinguished from the need for greater management ability. Typical procedures for evaluating the performance of alternative systems do not give enough attention to farmers' management ability and use of information. This is also true for research on conventional systems, even though in such systems information and management are not usually considered to have such a critical role.

In this paper, we criticize recent definitions of sustainable agriculture as being overly based on short-term economic criteria, rather than long-term ecological criteria. A concise definition of sustainable agriculture is put forth, premised on the assumption that the ecological parameters of energetics and ecosystem integrity ultimately determine the long-term viability of farming systems. We share with others the view that, in designing sustainable farming systems, a broad array of social and economic factors should be taken into consideration. We believe, however, that these factors are not intrinsic to a sustainable agriculture, but rather separate, desirable goals.