U.S. crops have the potential routinely to produce 15–25% more, and in some cases 100% more, with no more water or fertilizer, but are prevented from doing so by diseases, nematodes, arthropod pests, and weeds. It is not compatible with the goals of a sustainable agriculture to fertilize, cultivate, and water for maximum production, but then allow diseases and pests to limit actual yields to some fraction of what was paid for with the capital investments and agronomic inputs. In eastern Washington and adjacent northern Idaho (The Palouse), wheat generally yields 4,800–6,200 kg/ha in years of normal precipitation (45–55 cm), but yields 6,900–9,000 kg/ha with the same water and fertilizer if the soil is fumigated to eliminate root disease organisms and weeds, and the plants are protected from rusts, pseudocercosporella foot rot, and aphids. Some practical alternatives to soil fumigation (depending on the value of the crop) include crop rotation, tillage, flooding the soil, heating the soil (using clear plastic tarp or by burning residue on the soil surface), and organic amendments that intensify the biological stresses on pathogen propagules in soil. Other disease controls include using pathogen-free planting material, maintaining a diversity of genetic resistance, and adjusting planting date and method of seeding to escape pathogens. Some of the emerging technologies include improved serological and molecular methods for diagnosing pathogens, microorganisms that kill pathogen propagules in soil or protect the plant, simulation models of epidemics to forecast disease outbreaks, and integrated pest management systems. Better experimental a pproaches are needed to identify and determine the priorities of the combinations of biotic and abiotic factors that limit yields, and more attention should be given to holistic plant health care.

Many of the characteristics of common purslane that describe this species as a “weed” are also desirable traits for a living mulch. Common purslane was investigated as a living mulch in spring broccoli production in Connecticut and was compared with mechanical and chemical weed control, as well as black plastic mulch. Common purslane seed was broadcast prior to transplanting broccoli in late May 1993 and in early June 1994. Broccoli yields with the purslane living mulch were comparable to yields with conventional methods of weed management and with no reduction in crop quality. Common purslane living mulch was able to effectively compete with weeds in broccoli when between-row areas were kept relatively weed-free by hoeing or hand pulling during the first 2 weeks after broccoli transplanting. High levels of weed control and ground cover occurred when purslane became established between crop rows. Broccoli plants were tolerant of purslane living mulch and weeds up to a critical threshold level without a significant reduction in yield. Purslane living mulch established through periodic mechanical weed management was determined to be the most economical treatment in the study. While including purslane living mulch in a spring broccoli crop production system may be a novel approach to controlling weeds, the strategies involved in this system still rely on basic weed management principles.

Survey data from sweet corn, strawberry, apple, and potato growers in nine northeastern U.S. states were used to assess relative levels of adoption of integrated pest management (IPM). Grower adoption of an IPM system was measured by assigning numerical values for completion of specific management practices, and summing the number of practice points. Practices included those for management of soil, nutrients, weeds, diseases and insects, and education. Numerical scores were used to describe IPM adoption as a continuum, with growers classified as low, moderate, or high adopters based on their completion of practices. The relative level of IPM adoption varied among crops and states. Forty-nine percent of sweet corn growers were found to be moderateto high-level IPM adopters, while 76% of strawberry growers, 90% of potato growers, and 69% of apple growers were moderate- to high-level adopters, respectively. Variation among states with respect to adoption of IPM is described and discussed.

The March 1989 food safety episodes involving Alar on apples and the cyanide tainted grapes found in a Chilean shipment were seminal events in the history of U.S. organic agriculture. Demand for organic produce soared as a consequence of these events, and mainstream supermarkets began adding more organic produce to their traditional product lines. But when organic supplies proved scarce, and as prices increased, consumer purchases decreased and many marketing managers began to question the rationality of allocating scarce shelf space to organic products. In fact, many supermarket chains either drastically reduced their organic offerings or dropped them altogether. Some analysts proclaimed that organics had failed the market test. However, two surveys we carried out in 1989 and 1991 among major California supermarket chains show that forecasts of the demise of organic produce in mainstream markets may have been premature. Of 16 chains responding to our survey, 12 continue to carry organic produce. All had carried organics for more than six months, two-thirds of them for more than a year. Of the 12 that carry organics, six rate organics as worse overall than conventional produce. But, interestingly, six rate organics as “about the same” as conventional produce. This is a significant achievement for organics. Organics rated better on environmental impact and residues, worse on appearance and shelf life, and “about the same” on flavor and nutritive value. Despite the constraints and difficulties encountered in marketing organic foods, 8 of the 12 chains that carry organics would carry more organic fruits and vegetables if supplies were available. The prospects for certified “pesticide free” produce are less definite.

An areawide program for biological control of the alfalfa weevil showed expected economic benefits of $2.2 billion, expressed in present value terms. Alfalfa producers and consumers of livestock products are the main beneficiaries. The control program was highly successful, with a benefit/cost ratio of about 91. Not all areawide biological pest control programs will be as successful; a benefit-cost analysis like the one described here should be performed before areawide control is initiated to identify programs expected to provide economic benefits.

A survey of organic farmers in New York State identified problems in need of university research. Weed management was the most frequently mentioned problem by far, identified as significant by two-thirds of the organic farmers. Only a few other problems were listed as significant, including insufficient time for farm work, lack of markets, low prices, and lack of appropriate tools. These were cited by more than a third of the farmers. Drought, insect management, and a lack of a dependable supply of labor were cited by about one-third of the respondents. The survey also examined organic farmers' information sources. They do not use conventional sources of agricultural information, such as the extension service and conventional agricultural media, as much as books, magazines, and newsletters on organic f arming, other organic f armers, and on-farm experiments. Many respondents noted that local extension agents did not know very much about non-chemical solutions to organic production problems. They considered University Extension to be accessible, but not very useful in solving problems specific to organic farming, and had many suggestions to improve Land Grant research in organic agriculture.

Nonpoint sources of P pollution have been implicated in the declining water quality of many lakes in the northeastern U.S. Most of the agricultural nonpoint P contribution to surface waters comes from field runoff. Water quality may be improved by better understanding the movement, or flow, of P through a farm so that reasons for buildup of high soil P levels can be identified and remedies explored. In this study, the managed flows of P (P in imported and exported products) were estimated based on 1hour farmer interviews on 45 Vermont farms and 1 New York farm. Farm P inflow/outflow budgets were developed using information from the interviews. It was estimated that an average of 57% of the P brought onto the farms was not exported. Phosphorus imported in feed and minerals averaged 65% of the total P imports, while purchased fertilizer contributed to an average of 35% of the total farm P imports. Phosphorus was often fed in excess of the cow's nutritional requirements recommended by the National Research Council. Soil test P levels on two pairs of farms with similar animal densities and soil types reflected the large differences in the estimated net P accumulation. For all 46 farms, there was a significant relationship between net P accumulation and animal density (r2 = 0.59). Farms grouped by management operation type (confinement, pasture - based [non-organic], and pasture-based [organic]) were different in average farm size, animal density, P imports, net P accumulation, milk production, and predominant crop. Feeding of excess P results from the high P levels recommended by feed salesmen and nutritionists, who typically take into account the available home-grown forages and provide the suggested needs for purchases of concentrates and minerals. In a survey of seven Vermont dairy feed consultants and salespersons, rations were designed to feed cows as much as 50% more P than research has indicated is necessary.

One of the major gaps in the empirical literature comparing conventional and organic farmers is the degree to which conventional farmers would prefer or can be motivated to use reduced-input practices comparable to those of alternative agriculturalists. This paper presents the results of a 1987 survey of a random sample of New York farm operators and a two-thirds sample of the membership list of the New York State chapter of the Natural Organic Farmers Association (NOFA-NY). The results show that while conventional farmers tend to have a lower preference for reduced-input practices than do alternative agriculturalists (NOFA-NY members), conventional farmers tend to prefer pest- and disease-resistant crop varieties, nonpurchased, on-farmproduced sources of fertility, and nonchemical means of disease control over high-input, chemically-based production practices. The largest differences between conventional and alternative agriculturalists are with respect to preferences for weed control practices. For six of the eight practices assessed, operators of small farms (annual gross sales less than $40,000) were intermediate in their preferences between commercial-scale farmers (gross sales $40,000 or more) and alternative agriculturalists. There was, however, virtually no difference between conventional and organic farmers in their tillage practice preferences; similar percentages of the NOFA members and commercial-scale farmers preferred minimum tillage practices, while the percentage of small farmers preferring to use as few tillage operations as possible was lower than that of both commercialscale and organic farmers. Differences between conventional and organic farmers in their production practice preferences are far smaller than differences in their environmental orientations.

A traditional flooding practice showed promise for reducing pesticide use in Massachusetts cranberry beds. The 4-week long spring flood, termed “late water,” checked pressure of two of the most prevalent and severe management problems, cranberry fruitworm (CFW) and fungal finit rots (CFR). Fruit rot generally was equal or lower and infestation of fruitworm was consistently lower at the late water beds compared with unflooded beds, even though no fungicides were used for CFR control (standard practice is two or three applications per season) and insecticide applications for CFW were cut by almost 70%. Although there were no significant reductions in yield in two of the years studied, a significant decline (about 25%) occurred on late water beds in one year for unknown reasons.

Crops grown on sand and gravel spoil areas are subject to temperature, moisture, and nutrient stresses due to the infertile, acidic, and coarse-textured properties of the spoil material. Additions of organic materials such as feedlot manure and sewage sludge compost applied at rates of 40, 80, and 160 Mg/ha were found to improve these spoil areas by providing (1) a more favorable pH for seedling germination and root development, (2) essential crop nutrients, and (3) a greatly increased water content of the spoils in the treated plots compared to fertilized controls. The manure-treated spoil plots had a higher water content than either the compost-treated spoils or the limed and fertilized control plots. In a drought year when the wastes were reapplied, both grain and stalk yields of sweet corn were highest for the manure-treated plots. The low heavy metal content makes these organic materials safe for use as soil conditioners. In addition, uptake and accumulation of toxic metals by sweet corn is generally less than other crops. The interaction between the kind and rate of organic amendment applied, the amount of rainfall in any given growing period, and the water content of the treated spoils determined the final nutrient composition of the stalks, leaves, and grain, as well as the grain and stalk yield.

Living mulches are vegetative covers that can be grown in association with row crops to reduce soil erosion, improve trafficability and suppress weeds. Interference by the living mulch can reduce yields of an associated crop. The interference between a white clover (Trifolium repens L. ‘New Zealand’) living mulch and sweet corn (Zea mays L. ‘Golden Jubilee’) was studied using an established clover sward that was mowed and then sprayed with 1 to 1.5 kg ai/ha of atrazine. Corn was planted at different densities and planting arrangements into a narrow band tilled in the clover. Interference by clover reduced corn yields by 12 to 39%. However, when corn row width was reduced from 0.76 to 0.38 m, competition among corn plants declined; they became more vigorous and clover- suppress ive and reached even higher yields than conventional (no mulch) corn in 0.76 m rows. Similarly, sweet corn planted at a range of densities into a clover mulch killed by atrazine yielded more in equidistant planting than in wide (0.76 m) rows. A near equidistant corn planting arrangement can be a low-input alternative to achieve season-long clover suppression and thus minimize clover's competition with the intercropped corn.

Over 61% of farmers who sell agricultural products through farmers' markets are satisfied with the returns they generate. Producers who are 50 years of age or older and those who retail at least 70% of the dollar value of the products are more likely to be highly satisfied with their profit margin from farmers' markets. A strong positive relationship is documented between profit margin satisfaction and growers who offer organic produce for sale. Furthermore, the results suggest that producers with farmers' market businesses in the growing stage are more likely to be highly satisfied with profit margins.

Wood residues are applied to soils to improve their organic matter content and related biological, physical, and chemical properties. We monitored the changes in soil total C and N content, the bacterial, fungal and actinomycetal populations, and microbial biomass and activity during 20 weeks in the first season following the application of chipped wood from twigs (CWT), and as residual effects during the second growing season on a loamy soil (coarse loamy, mixed, frigid, Humic Fragiorthod) in Sainte-Brigitte-des-Saults (Québec) Canada. Wet-aggregate stability and the content of nutrients of the soil also were determined. Adding CWT stimulated the bacterial and actinomycetal populations very rapidly (within 8 weeks); in the second season the effect was less pronounced and gradually disappeared. The most significant and long-lasting effect was on the fungal population in two consecutive years of observation, with increases of up to 24-fold. This stimulation of fungi possibly was responsible for the large and significant increase in wet-aggregate stability observed in the second year. The effect of CWT on alkaline phosphatase activity and total C and N was observed only in the second season. Some immobilization was seen only in the season immediately following residue application. The addition of the CWT also supplied micronutrients, in particular Zn, which would make it a useful source of some elements in deficient soils. Application of CWT to this soil greatly improved its quality, as revealed by its biological, chemical, and physical attributes.

Permanent pastures produce far below their potential, as they are usually managed in the northcentral and northeastern United States. Dairy farmers in these regions generally feed their cattle year-round from stored forage and purchased concentrates, and use permanent pastures as mere holding or exercise areas, grazing them continuously. This practice involves high operating costs that, combined with lower milk prices, have resulted in greatly reduced profit margins. Farming practices that return more net income are needed. The Voisin system of rotational grazing management, which applies intensive management to forage crops on pastureland, is widely used on dairy and sheep farms in New Zealand. Farmers using the Voisin system there have low operating costs and obtain high yields of excellent quality forage over long grazing periods; increased net income results Between 1 May and 1 October 1984, 497 forage samples were taken and analyzed from permanent pastures grazed according to the Voisin management system on six Vermont dairy farms. This was done to provide farmers with current estimates of forage feeding value so that they could balance their cows' rations accordingly throughout the season, and determine if they could improve the profitability of their farms by using Voisin grazing management. Average grazingseason analyses (dry weight) were: 22.5% dry matter, 22.4% crude protein, 20.8% available protein, 28.4% acid detergent fiber, 1.18% calcium, .48% phosphorus, 1.60% potassium, .22% magnesium, and 1.58 Mcal/kg net energy lactation. Average dry forage yield was 8.9 metric tons/ha. Dry matter intake was adequate for milk production up to 36 kg/cow/day. Forage protein and energy contents were sufficient for at least 25 and 18 kg milk/day, respectively. On three farms where economic factors were calculated, net profits per cow averaged $67 more during the 5-month period from using Voisin grazing management, compared to continuous grazing of the same pastureland in the year before Voisin management was used. This profit resulted mainly from feed savings and a more favorable milk:concentrate ratio of 4.1:1 obtained with Voisin management, compared to 2.7:1 with continuous grazing and more feeding of stored or machine-harvested forage. Voisin-managed pastures can produce high yields of excellent-quality forage that can be incorporated into dairy feeding programs, thereby reducing feed costs and increasing profitability of the farming operations.

Practical Farmers of Iowa was founded in 1985 to help farmers generate and share information on environmentally sound farming methods. Its on-farm research trials allow farmers to do statistically valid comparisons of competing techniques, such as different weed control methods. However, sustainable agriculture means more than providing farmers with adequate information about appropriate techniques. It also requires policies that reward farmers for adopting sustainable methods and that support rural community well-being.

The transformation of agriculture according to an industrial model has had clear benefits in improving efficiency and lowering production costs, but also has had adverse consequences on rural culture and the environment. Sustainable agriculture offers alternative practices and values intended to promote environmental stewardship, conserve resources, preserve farm traditions, and support rural communities. Strong arguments can be made that it will have these consequences, based on the interactions among agricultural structure, rural community viability, and environmental quality. However, counterarguments can also be made, and the claimed benefits of sustainable agriculture for rural communities must be regarded as not yet demonstrated.

Interest in reducing purchased chemical inputs to reduce production costs and avoid possible environmental damage prompted this 7-year study. Two management systems, current management practices (CMP) and reduced chemical inputs (RCI), were evaluated for four crop sequences from 1985 through 1992: continuous grain sorghum; continuous corn; a 2-year rotation of corn and double-cropped winter wheat and soybean; and a 4-year rotation of corn, winter wheat/soybean, corn, and red clover hay (changed in 1989 to a 3-year rotation of corn, red clover hay, and wheat/soybean). No-till planting and recommended rates of fertilizer and pesticides were used in the CMP system. In the RCI system, N was supplied by a crimson clover green manure crop or the red clover in the rotation. Weed control was by chisel plowing, disking, and cultivation.

Crimson clover top growth accumulated from 70 to 180 kgN/ha, red clover from 77 to 130 kg N/ha. Rotating crops increased corn yield with CMP but not with RCI. lndry years, corn yields were low (less than 3000 kg/ha), corn did not respond to fertilizer N, and yields generally were higher with CMP than with RCI. With adequate rain, yield of all RCI treatments were the same as yield in CMP continuous corn receiving no fertilizer N. Johnsongrass competition was the main reason for low yields in the RCI treatments. Soybean yields were higher with CMP in 4 years and higher with RCI one year. Wheat and grain sorghum yields were higher with CMP than with RCI. A dramatic decline in johnsongrass in sorghum was noted in 1989, and several plots remained relatively free of johnsongrass through 1992.

Management decisions made during the experiment included the degree of input reduction in RCI; whether to either end or modify unproductive treatments; whether to use newly available varieties and pesticides; whether to suspend the experiment to eliminate johnsongrass; and how to add new treatments while retaining the original treatments.

Research aimed at advancing conservation farming practices is typically performed using traditional scientific approaches, which have been highly successful in increasing agricultural output and efficiency. With the current emphasis on environmental and economic sustainability of agriculture, there is a need for a more integrated approach to applied agricultural research. Participatory research helps to bring scientific methods and the integrated production needs of farmers together to develop practical, effective, and carefully tested farming methods. The strength of participatory research is in the synergism of scientists and farmers working together to design, implement, and evaluate research. The development of new technologies for farming systems large or small, conventional or organic, can be greatly enhanced through more extensive use of participatory research.

Cover-crop residues left on the soil surface as a mulch in no-till crop production systems protect the soil from erosion, increase water infiltration and suppress weeds. Because many growers using cover crops want to reduce chemical inputs, non-chemical methods of killing or suppressing cover crops are needed. In the first part of this paper we review the current literature and discuss advantages and disadvantages of five mechanical methods for killing cover crops, i.e., mowing, rolling, roll-chopping, undercutting and partial rototilling. We also report on three new studies that broaden the current literature, including planting into freshly killed residue. In the first study, the use of planter attachments to remove surface residues from the planter row improved stands when cotton was no-till planted 2–7 days after mowing cover crops in Mississippi. In the second study, 100% of a rye/vetch cover crop in Missouri was killed by mowing, and greater than 90% was killed by roll-chopping. Cotton stands were reduced by the use of row cleaners that clogged when the cover crop was roll-chopped or mowed on the same day that the crop was planted. The third study evaluated three methods of mechanically killing summer cover crops in North Carolina. Undercutting provided greater than 95% kill for five of six broadleaf species, and two of five grass species. Mowing effectively killed all six broadleaf cover crops, but re-growth occurred with three of five grasses, with the exception of nearly mature German foxtail millet and mature Japanese millet. In general, rolling did not effectively kill broadleaf or grass cover crops, with the exception of nearly mature German foxtail millet, mature Japanese millet and mature buckwheat.

Multidisciplinary approaches are being attempted by agricultural research units along with their traditional single discipline approaches. Although single discipline research will still be needed, multidisciplinary approaches present special advantages.

The potential value of multidisciplinary approaches to sustainable agriculture research will be viewed differently by researchers with different perspectives. The participants in this symposium, all of whom were experienced sustainable agriculture researchers, identified five areas as keys for success. First, to capitalize fully on the opportunities it provides, there must be a justification for using a multidisciplinary approach for the specific research topic; while some projects work best with a multidisciplinary approach, others are best done within a single discipline. Second, everyone involved, including administrators, must invest time and money to establish communication between the disciplines. Third, careful attention must be given to forming and operating multidisciplinary teams effectively so that they generate shared benefits. Fourth, new sources of research funds will become available as agencies adopt multidisciplinary approaches, and revised systems will be required to administer those funds at the university or research unit level. Finally, major adjustments in the present systems for promotion, tenure and publication are necessary to properly measure and distribute credit.