Raymond P. Poincelot

Agroecology: The Ecology of Food Systems

ABSTRACT We present a compelling rationale for defining agroecology as the ecology of food systems. Our purpose is to provide a framework that will guide research, education, and action in the multiple and interacting facets of an increasingly complex global agriculture and food system. To accomplish such goals, it is essential to build bridges and connections among and beyond our disciplines in production agriculture, as well as beyond the farm gate into the rural landscape and community. Fields of sociology, anthropology, environmental sciences, ethics, and economics are crucial to the mix. They provide additional vantage points from which we can view the food system anew, as well as insights on how to establish valuation criteria beyond neoclassical economics. Examples from Mexico, California, and the Nordic Region are used to illustrate the successful implementation of this educational strategy in universities. Design of individual farms using principles of ecology is expanded to the levels of landscape, community, and bioregion, with emphasis on uniqueness of place and the people and other species that inhabit that place. We conclude that defining agroecology as the ecology of food systems will foster the development of broader interdisciplinary research teams and attractive systems-based courses for tomorrows best students. In contrast to the narrow focus on crop-soil interactions, this definition will help us raise higher-level research questions whose solutions will advance the development of a sustainable agriculture and food system.

Rapid isolation of mesophyll cells from soybean leaves

Abstract A simple, rapid, mechanical procedure for the isolation of intact mesophyll cells within 2–3 min from soybean leaves is described. The identification of isolated mesophyll cells was made by light microscopy. Contamination of the preparation by chloroplasts was minimal. The intactness of the plasmalemma was checked by Evans blue impermeability, phase contrast microscopy, the ability to be conversted to protoplasts and the specific exclusion of lipophobic protein modifiers. Maximum rates of photosynthesis by these cells occured at 35°C, pH 7.8, 4 mM HCO 3 , and 800–1200 μE/m 2 /s (400–700 nM). A pre-illumination period of 5 min was essential for maximum rates of photosynthesis. Photosynthesis rates with the isolated mesophyll cells averaged 150 μmol CO 2 /mg chlorophyll/h for preparations made over a period of several months and occasionally approached 300μmol/mg chlorophyll/h.

Sustaining the Environment

Agricultural activities have had a definite impact upon the surrounding environment. Effects that have been noted include water, soil, and air pollution. In turn, indirect effects upon animal and even human life have been observed. Unhappily these impacts have resulted in a reduction of environmental quality.

Greenhouse Energy Conservation

Greenhouse agriculture is particularly vulnerable to problems of energy cost and disruption. Energy usage in greenhouses is concentrated, critical, and quite costly, whether growers operate in the North or South. For example, about 80% of the heating fuel in northeastern greenhouses is consumed in 5 months, November through March; 3 months, December through February, account for two-thirds of that usage. A disruption of energy on an icy cold day or extremely hot day could mean a disastrous loss of crops, or a sharp increase in energy costs could create serious cash flow problems. Fortunately, considerable energy savings are possible by modification of existing structures and by innovative designs of future facilities.

Sustaining Resources: Soil

Farmers, with notable exceptions, have benignly neglected the future farmers and their soil reserves. Exceptions include organic farmers and other conservation-minded farmers. With others the view is toward profits now and let other generations worry about the future. In all fairness their actions, although not the best choice, are understandable. Farmers have very large capital investments in land, equipment, seeds, fertilizers, fuel, and pesticides. Their profession often does not generate high yearly profits and disaster is sometimes only a change in the weather away. Many are financially overextended and faced with credit problems. Operating so close to the margin, they grasp at short-term profits and can ill afford the long-term investment needed for sustaining the soil.

Postproduction Energy Conservation

We have already examined agricultural energy input for crop and livestock production. These segments of agriculture together account for 18% of the energy utilized in the food system. The remaining energy usage, 82%, occurs beyond the farm gate. Postproduction energy is needed for transportation, processing, marketing, and preparation of food. At least 75% of U.S. crops and livestock are processed in some way before marketing to consumers.

Crop Energy Conservation

Today the food-producing capacity of American agriculture is unsurpassed by that of any foreign power. The efforts of farmers and agricultural scientists over the last 40 years are responsible for this great achievement. Since 1950 these efforts have resulted in a doubling of productivity and a halving of agricultural labor (Price 1981). Much of the increase can be attributed to increased use of fertilizers and advances in pest control, plant and animal breeding, and mechanization. With the exception of results based upon plant and animal genetics, most of the efforts that increased productivity were energy dependent. The price of doubled agricultural productivity is high: a four-fold increase of energy input (Price 1981).

Sustaining Resources: Water

Shortages of water — the most limited of all agricultural resources — are more likely to cause agricultural problems in the near future than are soil erosion and environmental pollution. Competition for water occurs among the agricultural, industrial, public, and energy-producing sectors of the United States. Further restraints upon water supplies are also imposed by the need to maintain aquatic systems and to preserve the environment. As such the sustainability of agricultural water resources is the most pressing problem in U.S. agriculture.

Animal Husbandry Energy Conservation

Certainly the most criticized farm operation in terms of energy input versus output is livestock production. The efficiency of crop production is on the order of about 1 % of the incident solar radiation; an additional 10-fold reduction of energy occurs when crops are fed to livestock. Critics feel it would be more energy efficient to feed crops directly to humans. Livestock producers and many meat consumers feel otherwise. An examination of the facts may help to put the issue into perspective.

Our Threatened Agricultural Resources

Agricultural production in the United States has almost become synonymous with success. Certainly, no one would argue against its being a cornerstone of American greatness, nor suggest that the significant yield increases and corresponding labor decreases of the past several decades were undesirable. Certainly not. Yet, an uneasiness has begun to surface in certain quarters, as the long-term costs of American agriculture gradually become apparent.