Strip-farming

In the United States, soil conservation first became an important political issue in the 1930s, when President Franklin D. Roosevelt led a campaign to study the loss of valuable topsoil because of erosion . It soon became clear that one source of the problem was the fact that farmers tended to plow and plant their fields according to property lines, which usually formed squares or rectangles. As a result, furrows often ran up and down the slope of a hill, forming a natural channel for the runoff of rain, and each new storm would wash away more fertile topsoil. This kind of erosion resulted not only in the loss of soil , but also in the pollution of nearby waterways.

The Soil Conservation Service was founded in 1935 as a division of the U.S. Department of Agriculture , and one of its goals was the development of farming techniques that would reduce the loss of soil. One such technique was strip-farming, also known as strip-cropping. Strip-farming involves the planting of crops in rows across the slope of the land at right angles to it rather than parallel to it. On gently sloping land, soil conservation can be achieved by plowing and planting in lines that simply follow along the slope of the land rather than cutting across it, a technique known as contour plowing . On very steep slopes, a more aggressive technique known as terracing is used. Strip-farming is a middle point between these two extremes, and it is used on land with intermediate slopes.

In strip-farming, two different kinds of crops are planted in alternate rows. One set of rows consists of crops in which individual plants can be relatively widely spaced, such as corn, soybeans, cotton, or sugar beets. The second set of rows contains plants that grow very close together, such as alfalfa, hay, wheat, or legumes. As a result of this system, water is channeled along the contour of the land, not down its slope. In addition, the closely planted crops in one row protect the exposed soil in the more widely spaced crops in the second row. Crops such as alfalfa also slow down the movement of water through the field, allowing it to be absorbed by the soil.

The precise design of a strip farm is determined by a number of factors, such as the length and steepness of the slope. The crops used in the strip, as well as the width of rows, can be adjusted to achieve minimal loss of soil. Under the most favorable conditions, soil erosion can be reduced by as much as 75% through the use of this technique.

See also Agricultural pollution; Agricultural technology; Soil compaction; Soil loss tolerance

[Lawrence H. Smith ]

RESOURCES

BOOKS

Enger, E. D., et al. Environmental Science: The Study of Relationships. 2nd ed. Dubuque, IA: W. C. Brown, 1986.

Moran, J. M., M. D. Morgan, and J. H. Wiersma. Introduction to Environmental Science. 2nd ed. New York: W. H. Freeman, 1986.

Petulla, J. M. American Environmental History. San Francisco: Boyd & Fraser, 1977.