An explanation is provided of why and how one group of researchers in a Chinese village setting came to focus on what the authors call biological recycle farming. An explanation of applied agricultural research in China is provided. One conclusion reached is that application of research at the village level was largely successful because it was founded on community development principles. Another conclusion is that food production in very marginal Chinese villages can be increased significantly. While the alternative approach discussed cannot be exported wholesale to many other countries of the world, the concepts are very useful for international economic and agricultural development.

Recently there has been a change in thinking among many agricultural leaders and researchers toward a major focus on agricultural sustainability. To make progress toward such sustainability requires a clear delineation of its concepts and components. In this paper, I attempt to clarify relevant concepts and terminology in an effort to facilitate communication and cooperation. I also recognize, however, the intense feelings involved in these definitions. More satisfactory definitions will come in time as research and practice continue.

Few plant breeding programs involve attempts to develop varieties specifically adapted to low-input cropping systems. Plant breeders generally select varieties in highly fertile, weed-free, densely seeded environments. However, alleles needed for achieving maximum yield in low-input environments often differ from those required in highinput conditions. Thus, when effective selection can be undertaken under low-input conditions, breeding programs specifically targeted at low-input environments should produce the best varieties for those environments. Experimental protocols for identifying such situations are described in this review. These involve (a) testing breeding lines under low- and high-input conditions, (b) estimating both the degree to which yields from the two types of environment are controlled by the same alleles and the relative accuracy with which superior genotypes can be identified in low- and high-input environments, and (c) predicting the direct and indirect responses to selection at each input level. On the basis of published data, it seems feasible to develop corn hybrids specifically adapted to production with lower rates of N application than are now commonly used in the United States.

A review of orchard soil management effects on tree growth and soil parameters is presented. It shows the gap between present common practices and results achievable in other systems. An alternative soil management system for newly planted peach trees, termed “killed-sod”, is described. This system has improved soil structure and rainfall infiltration and greatly increased early tree growth and yield. A fertilization study has demonstrated that the addition of a complete fertilizer in four different soil management systems could not account for the increased growth resulting from the improved soil environment in the killed-sod system.

This study seeks to identify the social factors related to opposition to government regulation of agricultural chemicals and pharmaceuticals. Analysis of data from a 1982 survey of farm operators in New York State shows that, in contrast to much of the literature that represents farmers as being almost universally opposed to regulation, farm operators' orientations toward government regulation of these substances vary considerably. Indicators of the class status or position of farm operators were found to be directly related to opposition to regulation. Willingness to assume risk and the importance placed by farm operators on making profit were also directly related to opposition to regulation, while farm men's off-farm work, cynicism toward agribusiness, non-economic orientation toward agriculture, perceptions of potential side effects of agricultural chemicals and drugs, and liberal political attitudes were inversely related to opposition to regulation. The results of a multivariate analysis suggest that farmer opposition to government regulation of agricultural chemicals is primarily due to farmer ideology and has little relationship with whether farmers actually use these chemicals.

On-farm field demonstrations provide a useful method of technology transfer for researchers and extension specialists, and the proponents of alternative agriculture have adopted on-farm experimentation as an important means to establish the value of sustainable methods. For on-farm research long narrow strips harvested by machine are often employed in place of small hand-harvested plots commonly used at research facilities. The use of this approach, however, could bring the methodology into question if field variation should make determination of statistical differences difficult. Analysis of harvest data from ten irrigated and four dryland site-years for small hand-harvested corn plots and for machine-harvested long narrow strips was conducted to determine the impact of sampling method upon experimental variation. Analyses of variance indicated that six of the ten machine-harvested irrigated sites had significant yield response to applied nitrogen while only one of the ten hand-harvested sites exhibited significant nitrogen effects (P ≤ 0.10). The difference in statistical precision was not a result of increased range in yields, but rather of more consistent yields for each treatment. An economic analysis was performed, and the results indicated that optimum nitrogen rates depended on corn and nitrogen price ratios. When 1989 corn and nitrogen prices were used, the calculated marginal profit levels between the reduced nitrogen and recommended nitrogen rate ranged from $8.92 to -$8.14 per ha. For the irrigated sites, when experimental variation (F-test of total sum of squares) was compared by harvest method, hand harvest had significantly greater variation than machine harvest in five experiments. Machine harvest was significantly more variable in one comparison. Coefficients of variation for machine harvest were less than for hand harvest in nine of ten irrigated experiments. For the dryland sites, differences between harvest methods were significant in one of four experiments. These data suggest that under certain conditions machine-harvested long narrow strips provide more accurate estimates of treatment differences than do small hand-harvested plots despite potential differences in soil texture, soil fertility, or available soil water.

This paper analyzes some of the potential problems that can be anticipated in putting a sustainable system together on an operating farm, and proposes a few of the principle practices and management strategies required for making such systems work.

Winter legume cover crops are receiving increasing attention from agronomists and farmers as a source of nitrogen for summer crops. While agronomists are continually providing new technical information on using legumes as a nitrogen source, little is known on the economics of their use. Previous economic research on legume cover crops has focused mainly on budgeting analysis. In the present work, a twofactorial experiment was designed to test the use of legumes as a nitrogen source for corn (Zea mays L.) in north Georgia. The first factor was winter cover crop with treatments being crimson clover (Trifolium incarnatum L.), hairy vetch (Vicia villosa Roth), wheat (Triticum aestivum L.), and no cover crop or winter fallow. The second factor was nitrogen (N) fertilizer applied at five different rates: 0, 25, 50, 100, or 200 pounds per acre. For each combination of the two factors, mean yield and yield variance were determined. Results indicated that legume cover crops increased both average corn yield and yield variance. The greater yield variance from the use of legume cover crops increases economic risk. Risk-averse farmers must be compensated for increased profit variance by higher average profits. A safety first method was used to evaluate the tradeoff between average profit and profit variance for the risk-averse individual The results showed that hairy vetch with 50 pounds of N per acre was the best combination of cover crop and fertilizer rate for risk-neutral farmers. For risk-averse farmers, hairy vetch without any nitrogen fertilizer is preferred.

The positive role of biological diversity in enhancing agricultural sustainability is presented in the context of crop rotation. Once common in virtually all farming systems, crop rotations have been simplified or eliminated during the past two decades from farming systems in most industrialized countries. Specialization, production intensification, government commodity programs, and the resulting short-term economic decisions have all had an influence in reducing crop rotation and diversity. Economic and environmental concerns have raised the question of agricultural sustainability in the public arena. We discuss here the role of diversity and crop rotation in relation to the sustainability issue, including matters of agronomic, economic, and environmental benefits, as well as increased efficiency in the use of fossil fuels. Constraints and future directions in the use of crop rotation in modern agriculture are described.

The market value for organically grown produce in California was estimated to be at least 54 to 68 million dollars at wholesale prices in 1987. This market is rapidly growing. A 41 percent increase in the value of organically grown produce was observed in 1987. When this analysis was completed in early 1988, it was estimated that the wholesale value of the market could exceed $300 million by 1992. A sample analysis of 1986–1987 price and volume for organically grown broccoli showed relatively steady prices and a volume increase of over 50 percent, indicating a similar growth in market demand. Prices for organically grown produce are significantly higher than for conventional produce; however, in spite of high weekly volume volatility, organic prices appear to be less volatile than prices for conventional produce. This paper proposes that the collection, reporting, and analysis of organic produce market data be continued and improved and that new sources of data be integrated to ensure continued availability of timely market information. Availability of more market information should increase efficiency and aid the development of the organic produce industry. The paper also proposes that overall trends in the organic produce industry be systematically monitored by Federal-State Market News and that the increased use of market information by organic growers, growers considering the transition, and other interested parties in the industry be promoted.

Conventional, low-yield aquaculture methods use earthen, standing water fish ponds that typically are stocked with 0.5 to 2 fish/m2 and produce 3 to 10 tons of fish/ha/year using refined feeds. At higher fish stocking densities and fish yield, production of metabolites and residues exceeds such a pond's natural recycling capability, so that a higher rate of flushing is required. This wastes water and valuable nutrients and creates a potentially polluting effluent In an alternative system, by increasing the rate at which the metabolites and feed wastes are microbially processed within the culture system, production rates exceeding 500 tons of tilapia fish/ha/year have been attained with less than 0.5 percent water change daily. In preliminary experiments in this closed bioconversion system, we have replaced all formulated feeds with agricultural residues and fertilizers, which are converted into protein by intense microbial processing. The rate of fish growth indicated that much or possibly all the feed requirements of tilapia grown in this type of closed, densely stocked system can be satisfied by intense cultivation of heterotrophic microbes.