When defining sustainable agriculture we need to look at the history of organic farming, since sustainable agriculture arose out of this movement. The present paradigm of organic farming began as a melding of several different schools of thought that were supported by European and English scientists active in the 1920's, 30's and 40's. The essential role of a healthy, fertile soil in viable agriculture was the common thread that linked these schools of thought.

In particular, an Englishman, Sir Albert Howard developed many ideas that became some of the foundation of sustainable farming prior to World War II in India where he was trying to meet the challenge of improving farmers' yields in order to feed a rapidly increasing population. He believed that the best way to increase food productivity at a moderate cost was to return the organic by-products of crop production as well as animal manures to the soil. Howard also had concerns about the changes in soil chemistry caused by the use of synthetic fertilizers and the use of chemical poisons to solve all pest problems.

The Emergence of Sustainable Agriculture
In the 1950's and 1960's another movement, called the green revolution, evolved to meet the challenge of providing food for a rapidly expanding world population. This movement met the challenge from a direction that was diametrically opposed to that of organic farming. It emphasized genetically enhanced plant varieties and high-energy off-farm inputs such as mechanization, synthetic fertilizers and pesticides. In time this movement became 'conventional' agriculture and resulted in high food production at a low cost to the public, particularly in the United States.

As this movement developed some people became concerned that this type of agriculture could not be sustained in the long term. They felt that although the cost of food production was low, the dollar value of food produced with conventional agriculture did not reflect the true cost from an ecosystem and societal perspective. The true cost takes into consideration issues like air pollution from producing and using fossil fuels, soil degradation due to intense cultivation and use of synthetic fertilizers, habitat destruction, air and ground water contamination with fertilizers and pesticides, and the steady decrease of the farmer population as family farms were out-competed by corporate farms. These concerns over the long-term sustainability of conventional agriculture resulted in the development of the sustainable agriculture movement, which owes many of its farming approaches to the organic farming movement.

Definition of Sustainable Agriculture
In 1989 the American Agronomy Society adopted the following definition for sustainable agriculture: "A sustainable agriculture is one that, over the long term, enhances environmental quality and the resource base on which agriculture depends; provides for basic human food and fiber needs; is economically viable; and enhances the quality of life for farmers and society as a whole." The Sustainable Agriculture Research and Education Program at University of California, Davis (UC SAREP) emphasizes that sustainable agriculture integrates 3 main goals-environmental health, economic profitability, and social and economic equity.

UC SAREP also points out that a systems perspective is essential to understanding sustainable agriculture. Farming does not operate in a vacuum. Each farmer's field is part of a complex community ecosystem, which in turn can effect or be impacted by global economics and even global ecological processes (eg. El Nino). A systems perspective involves viewing multiple factors when considering field and farm-level decisions.

Things to keep in mind
Although the concepts of sustainable agriculture, organic farming and IPM (integrated pest management) have been around for a long time they are often misunderstood and can be controversial. It is important for everyone to realize that none of these is going to solve all problems all the time. Keep in mind that most crops are exotic (ie. non-native) to the farms on which they are grown, and most pests on these crops are non-native, too. This creates a potentially unstable ecological situation regardless of the type of farming being practiced. There are some crop/pest systems that are inherently unstable and crop damage is unavoidable without some outside intervention. A good example is codling moth in many orchard crops. Pests can even get out of hand in some fairly undisturbed, 'natural' ecosystems, as illustrated by periodic destructive epidemics of forest insects in certain forest ecosystems.

This essay was written by Protected Harvest founding board member
Dr. Cliff Ohmart, Director of Integrated Farming and Research at the
Lodi-Woodbridge Winegrape Commission in California.