We compared the agronomic, economic, and ecological performance of alternative (organic), conventional, and reduced-till farming systems over a 7-year period. We evaluated the sustainability of the various systems regarding several concerns, including soil erosion, pollution potential, whole-farm productivity, energy use, environmental stress, economic performance, and farm size. The alternative systems relied primarily on forage legumes (alfalfa or clover) as substitutes for the pesticides and commercial fertilizers used in the other systems.

Two studies were established in northeastern South Dakota in 1985. Study I emphasized row crops, Study II small grains. The alternative system in Study I, which included alfalfa hay in the rotation, was the most productive, both agronomically and economically. In Study II, the alternative system included a green manure crop (clover) in the 4-year rotation and had the lowest agronomic production; however, its economic performance was similar to the conventional system's. Year-to-year variability in production was lowest in the alternative systems. The alternative systems in both studies were the most energy-efficient, and the reduced-till systems the least. Judged by the distribution of nitrate-N in the soil profile, the potential for groundwater pollution was higher in the conventional and reduced-till systems in Study I than in the alternative system.

The alternative systems in both studies depended less on government payments for their profitability. Results in Study I also showed that more widespread adoption of alternative systems would tend to halt or slow the trend of ever-increasing farm size. These studies suggest that alternative systems are more sustainable in this agro-climatic area.

I interviewed 19 county agricultural extension agents about their views of alternative agriculture as it is being promoted by sustainable agriculture groups in Minnesota. They varied considerably in how much they knew about it, their openness to it, and how heavily they were involved in it County extension agents share broad economic and environmental goals with sustainable farming advocacy groups, but many believe that agriculture is already working to meet those goals and are skeptical of the feasibility of alternative agriculture. Extension agents generally did not accept as realistic a primary social goal of sustainable agriculture advocates: maintaining the number of family farms. If county extension agents and sustainable agriculture groups in Minnesota are to work together for more sustainable agriculture, open discussion is needed on the goals of agriculture and visions for its future.

We used linear programming to simulate adoption of manure disposal technologies in eastern Colorado. Manure, either raw or composted, is assumed to be applied to irrigated cropland within 20 miles of feedlots in five subregions of eastern Colorado. We constrained the application so that total N application is no more than the amount used by the crop. N, P and K contents are taken into account, but no benefits are assigned to organic matter or trace minerals and no costs are assigned to soil compaction, weed seed propagation, or inconvenience. Irrigated land within 10 miles of feedlots can easily absorb all manure generated under this scenario. Manure is found to be an economical substitute for chemical fertilizers, assuming N content to be at least 50% that of fresh manure. Composted manure is either more or less profitable than raw manure, depending on its N content. Hauling costs are lower for compost, but composting costs are between $1 and $2 per finished ton. The model does not allow for mixed application of compost and chemical fertilizers, which would increase the value of compost significantly. A feedlot waste sector that composted all feedlot manure in eastern Colorado is predicted to create between 80 and 200 additional jobs.

Two conventional cropping systems (winter wheat/dry peas and winter wheat/spring barley/dry peas) in the dryland grain region of southeastern Washington were compared with several alternative systems regarding profitability and environmental impacts. Two of the alternative systems use green manure crops and have low fertilizer and pesticide requirements. The remaining two are otherwise conventional rotations modified to include soil-building crops, bluegrass seed and rapeseed.

Estimates of annual off-site erosion damage ranged from $6.56 to $20.50 per rotational acre, while on-site damage estimates ranged from $0.50 to $1.55 per rotational acre. Estimated leaching losses of pesticides to a water table 3.6 feet deep were negligible, but significant leaching losses of nitrate-N were predicted to occur from fall-applied inorganic fertilizer.

Including bluegrass in a conventional grain rotation increased estimated net returns over variable costs by 16% and decreased soil loss by 33% compared with the most profitable conventional rotation. The next most profitable alternative system, rapeseed plus a conventional grain rotation, had slightly higher net returns over variable costs than the second most profitable conventional rotation, with slightly less soil loss. When fixed costs of machinery depreciation and land are included, the alternative systems fared relatively better. An experimental wheat/pea/medic system had higher projected net returns over total costs than the most profitable conventional rotation, while averaging just one-third as much soil loss per year. A wheat/barley/sweetclover green manure rotation was similar in profitability to the less profitable conventional rotation, but had only two-thirds as much soil loss.

We constructed a mixed-integer linear programming model to determine the profitmaximizing combination of conventional and alternative rotations under 1990 farm bill provisions. Planting all or nearly all land to the bluegrass plus conventional grain rotation maximized returns over total costs for high, medium, and low program crop price scenarios. Farmers maximized profit by participating in both the wheat and barley programs under the low price scenario, only in the wheat program with moderate prices, and in neither the wheat nor the barley program under the high price scenario.

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.

In a harsh, northern climate and under restrictive animal welfare laws and a strict ban on the use of subtherapeutic antibiotics, Swedish pig farmers have developed a managementintensive system of pig production that relies on straw, the animals' natural behavior, group housing dynamics, and keen husbandry skills. The system is very efficient, with excellent pig reproduction and growth performance. The housing is simple and versatile. Called “Västgötmodellen” after the region in western Sweden where it was developed by farmers during the 1980s, the system now is successfully used on approximately 100 farms in Sweden. The system is specific to producing feeder or weanerpigs of 25 to 30 kg for feeding in more conventional European-style finishing units. Västgötmodellen may represent an agricultural system that is well adapted and economically competitive on modest-sized farms but not well suited for very large farms.

Biodynamic and organic farming are similar in that both are ecologically oriented and do not use chemical fertilizers and pesticides. The main difference is that biodynamic farmers add eight specific amendments, called preparations, to their soils, crops, and composts. Recently, there has been an increasing interest in biodynamic farming practices and systems because they show potential for mitigating some detrimental effects of chemical-dependent conventional agriculture. Only a few studies examining biodynamic methods or comparing biodynamic farming with other farming systems have been published in the refereed scientific literature, especially in English. This paper summarizes data from previous studies, both published and unpublished (theses), that have compared biodynamic and conventional farming systems with respect to soil quality or profitability. These studies have shown that the biodynamic farming systems generally have better soil quality, lower crop yields, and equal or higher net returns per hectare than their conventional counterparts. Two studies that included organic management treatments with and without the preparations showed that the preparations improved biological soil properties and increased crop root growth. However, more research is needed to determine whether the preparations affect soil physical, chemical, and biological properties and crop growth and, if so, their mode of action.

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.

Nitrogen, a vitally important plant nutrient, is subject to various losses that affect its efficiency. We tested prilled urea (PU), urea supergranules (USG), green manures (GM) and farmyard manure (FYM) in a rice-wheat cropping system to determine which were the most efficient and economical N sources. The maximum rice growth, yield and N-uptake occurred with USG and with GM (Sesbania rostrata) plus PU. Incorporation of GM saved 60 kg N/ha. On the following wheat crop, GM (S. aculeata) plus PU and FYM plus PU had the highest residual effect on the number of tillers per m2, and straw and grain yield. An increase in N recovery efficiency occurred with combined use of PUand organic Igreen manures compared with PU alone. In areas where USG is costly or unavailable and FYM is scarce, green manures can be a cheap N source that allows small-scale farmers to get sustainable yields in a rice-wheat rotation.

The red sunflower seed weevil, Smicronyx fulvus LeConte, is a major pest of sunflower in North and South Dakota and Minnesota. Typically, insecticides are used to reduce oviposition and prevent economically damaging larval populations from developing. In a test of a reduced-pesticide alternative, we planted early maturing sunflower in the margins around commercial fields of oilseed sunflower. The margins flowered earlier than the field interiors and acted as a trap for the red sunflower seed weevil. They were treated with an insecticide while the trap rows were blooming and before the field interior began to flower. Conventional fields entirely treated with insecticide served as checks. We compared the trap and check fields with regard to yield, the fraction of larval-damaged seeds, and economic costs (insect damage and the cost of insecticide materials and application). Yield and larval damage of seeds were comparable between check and trap fields. However, the economic costs of weevil control in the check fields was greater than in the trap fields. Trap cropping is a recommended strategy for the red sunflower seed weevil, especially where economically damaging populations of the weevil are expected.

Five thoughts about the role and future of weed science in agriculture are analyzed. Much about the tools, techniques, and achievements of weed science should be lauded. Its achievements in basic science and its worldwide contributions to agricultural production and productivity are incontestable. The discipline has been based primarily on chemical technology, and the weed science community has been shaped by the available technology and by the purposes of its members. New, sustainable weed management systems will rely on knowledge derived from answers to new questions about weed-crop relationships and management techniques. As weed scientists develop better management systems, they will need to find better words to describe what they do and why it is important.