The negative environmental effects of agriculture water and air pollution, loss of habitats and biodiversity, greenhouse gas emissions, and nutrient losses have received major attention and continue to persist. Environmental concerns arise from many agricultural activities and sources including concentrated livestock production, pesticide and chemical use, deforestation, drainage of wetlands, soil erosion from cropland, and the use of fragile lands.Damage to SoilSoil erosion from farmland threatens the productivity of agricultural fields and causes a number of problems elsewhere in the environment. An average of 10 times as much soil erodes from American agricultural fields as is replaced by natural soil formation processes. Because it takes up to 300 years for 1 inch of agricultural topsoil to form, soil that is lost is essentially irreplaceable. The consequences for long-term crop yields have not been adequately quantified. The amount of erosion varies considerably from one field to another, depending on soil type, slope of the field, drainage patterns, and crop management practices; and the effects of the erosion vary also. Areas with deep organic loams are better able to sustain erosion without loss of productivity than are areas where topsoils are shallower.Erosion affects productivity because it removes the surface soils, containing most of the organic matter, plant nutrients, and fine soil particles, which help to retain water and nutrients in the root zone where they are available to plants. The subsoils that remain tend to be less fertile, less absorbent, and less able to retain pesticides, fertilizers, and other plant nutrients. Why then is erosion allowed to continue at excessive levels on many U.S. farms? Often the short-term costs of implementing erosion control measures far exceed the immediate economic benefit to the farmer, but such cost-benefit analyses fail to take into account the long-term losses of fertility and...
