8 Agriculture and Sustainability
Learning Objectives
After studying this chapter, you should be able to:
- Discuss how conventional agriculture affects ecosystems, economies, and human health
- Identify environmental effects of pesticides
- Recognize the relationship between exposure to persistent organic pollutants (POPs) and human health
- Explain alternative practices in farming and soil management
Conventional Agriculture
The prevailing agricultural system, variously called “conventional agriculture,” “modern agriculture,” or “industrial farming,” has delivered tremendous gains in productivity and efficiency. Food production worldwide has risen in the past 50 years; the World Bank estimates that between 70 percent and 90 percent of the recent increases in food production are the result of conventional agriculture rather than greater acreage under cultivation. U.S. consumers have come to expect abundant and inexpensive food.
Conventional farming systems vary from farm to farm and from country to country. However, they share many characteristics such as rapid technological innovation, large capital investments in equipment and technology, large-scale farms, single crops (monocultures); uniform high-yield hybrid crops, dependency on agribusiness, mechanization of farm work, and extensive use of pesticides, fertilizers, and herbicides (Figure 1).
In the case of livestock, most production comes from systems where animals are highly concentrated and confined. In the United States alone, over 10 billion land animals (cows, pigs, chickens, etc.) are used for food every year. Raising such a large number of animals on a limited amount of land requires animals to be housed in crowded, unsanitary conditions (Figure 2).
Both positive and negative consequences have come with the bounty associated with industrial farming. Some concerns about conventional agriculture are presented below.
Ecological Concerns
Agriculture profoundly affects many ecological systems. Negative effects of current practices include the following:
Decline in soil productivity can be due to wind and water erosion of exposed topsoil, soil compaction, loss of soil organic matter, water holding capacity, and biological activity; and salinization (increased salinity) of soils in highly-irrigated farming areas. Converting land to desert (desertification) can be caused by overgrazing of livestock and is a growing problem, especially in parts of Africa.
Agricultural practices have been found to contribute to non-point source water pollutants that include salts, fertilizers (nitrates and phosphorus, especially), pesticides, and herbicides. Pesticides from every chemical class have been detected in groundwater and are commonly found in groundwater beneath agricultural areas. They are also widespread in the nation’s surface waters. Eutrophication and “dead zones” due to nutrient runoff affect many rivers, lakes, and oceans. Reduced water quality impacts agricultural production, drinking water s