As we enter into the last decade of this century, the term 'sustainable' has become fashionable. It is evident is nearly every sector of our society. Sustainable development, sustainable agriculture, sustainable economies; even the term sustainable growth has been used. Obviously, not everyone is thinking of the same concept when using the word. For as much as the word sustainable has been used, a universal definition still does not exist. Why? What does it foretell about the future? And how does it apply to agriculture?

Wes Jackson, who spoke to you last year, has recently suggested that the term defies universal definition because it is not the property of a government agency or land grant university laboratory. Instead it came from the people and thus belongs to the people - all of them - whether from the south or north, rich or poor, urban or rural. The definition thus mirrors the diversity of its source. If we think back, it may not be that unusual for society to recognize a need for change before it actually knows what the problem is, much less exactly how to deal with it. The term sustainable agriculture might be in just that position now. As our society matures and our agriculture ages, few can deny the increasing problem in maintaining environmental quality, holding energy and cash input costs down, and the social dimensions of health and a shrinking rural society. Yet, we don't know exactly how to begin to change it. A sustainable agriculture is thus the challenge of the people - an agriculture that depletes neither our resources nor our people.

So what are the fundamental features of a sustainable agricultural system, and how far from it are we? This will surely be the focus of much future research. At North Dakota State University we have begun by not focusing in on the specifics, but standing back and taking in the whole. We are attempting to bring an ecosystem-level analysis of Northern Plains production agriculture to our aid in defining where and when our system can be improved. Once the specific practice or practices which are most environmentally or economics expensive are identified, alternatives can be explored. Hopeful solutions are then substitute back into the whole. A simple plan but often overlooked in agricultural research. We have traditionally spent our time only on components of the production cycle and usually in isolation from each other. Only if successful in contributing to the whole a more self-perpetuating, resource conserving and affordable agriculture, will the component be deemed successful.

Research on just what will leads to stable agroecosystems is being conducted around the world. We presently are focusing on two features which seem characteristic of most sustainable communities, 1) recycling of energy and mass, and 2) diversity.

Our present agriculture has a constant need for inputs: fertilizer, pesticides, and energy. Granted, what we haul from the field in the truck will have to be replaced if the system is to perpetuate itself, but the way we go about producing the crop itself may increase those requirements. Increasing use of tillage, pesticides, and fertilizer, especially nitrogen fertilizer which is energy dense, has created a growing appetite for energy. David Pimentel, from Cornell University in New York, has recently found the average U.S. Midwestern agriculture to require 140 gallons of oil per acre per year. Some practices, such as conservation and no-tillage, crop rotations, and the substitution of perennial for annual plants would go a long way in improving the balance. Traditional legumes will undoubtedly play a larger role in the future. There may also be room for other legumes, which can coexist with harvestable grains and sponsor at least some of the nitrogen fertility. Certainly, there is nothing magic about legume nitrogen as opposed to fertilizer nitrogen, but should the non-renewable energy sources currently used cost their real value, agriculture would not be able to afford ft. Using solar radiation to fix the nitrogen seems a longer-term solution.

Another aspect of recycling is rethinking what may be considered waste. Ruminants can readily use large grain farms with considerable crop aftermath and screenings gleaned from the grain. Likewise, it is not unusual to drive by a crop/livestock farm with a ten-year pile of manure accumulating like trash. Ironically, not only is unutilized livestock manure a lost asset, but it also becomes an environmental pollutant if not recycled. While these two examples may not fit every situation, most can find ways to make their farm more efficient by the recycling of resources internally, labor included.

We have greatly changed the form in which energy is used in agriculture. In a relatively short period of time, we have taken pesticides so for granted that we have created a growing environmental threat. Interestingly, earlier in this century it took about the same thirty years to create the dust bowl with mechanization. We may no a getting the message in an ominous cloud of dust, but is just as real - we will not be able to rely solely on pesticides in the future. The lesson is one we've learned before and will have to learn again. We can not substitute the use of our newest inventions for knowledge. We will have to discover the value of crop rotation, smart tillage, plant-to-plant interactions, and other biological solutions in today's economy. Many pesticides will probably revert back to being used only as emergency remedies. Again, we must look for long-term solutions which come from within the s am itself instead of always importing ft.

Diversity is another key feature of most sustainable communities. In agriculture we have replaced hundreds of plant species with a handful. The results of such an exchange are evident today in the increased susceptibility of our crops to disease, insects, and weeds. Crop rotations are an effective means of increasing diversity over time Multiple cropping techniques have the potential to increase diversity spatially. If carefully constructed, such techniques mimic the stability of natural polycultures. Soil, water, and solar resources are fully utilized and pests have a difficult time destroying the entire community.

Beyond recycling and diversity, close examination of sustainable communities, which contain people also posses, at least two other important characteristics. First, there is a close association between the natural economy and the artificial one. Soil, grain, labor, skill, and other products of society are only as valuable as they are useful in perpetuating the community. A single economic standard is important to maintain balance and resist the temptation of deficit spending. Unfortunately in our society, the gap between nature's economy and man's economy is continually growing apart. This double standard is a major roadblock in achieving a sustainable agriculture. The other trait of sustainable societies is the universal understanding that there are limits to growth. Our knowledge of science and nature tells us that sustainable growth is physically impossible, yet we continually try to defy this basic principal.

In summary, biological characteristics of sustainable communities include greater internal recycling and more diversity than our current agriculture communities. Socially, people within sustainable communities have a clear understanding of the value of their resources and limits to growth. The meaning of the word sustainable however, has much to do with an individual's outlook and the time frame he or she operates within. Evan growth is sustainable if we have a short enough time frame. Western Hemisphere agriculture as we know it has operated within a short time frame for a long time. The call for a sustainable agriculture is the challenge of extending that time frame. We have no more new land. We should not count on another new invention. Amore sustainable agriculture is a call for a greater vision and a secure future for the land and it's people.