The effects of erosion control practices, management, weather and soil properties on corn yields on soils of southwestern Iowa

Abstract

In many areas of the United States, soil erosion has become a serious agricultural problem and the State of Iowa is no exception. People attribute this to several causes but increased production of row crops is the principal cause. For example, Moldenhauer and Amemiya (196g) estimated that in the deep loess soils of western Iowa, a corn-corn-soybean rotation without erosion control can result in soil losses as great as 42 tons per acre annually from 9% slopes 300 feet long, or 27 tons annually from 6% slopes 400 feet long. This means that in only 20 to 30 years six inches of the top soil can be lost from soils that have an allowable loss of only 0.03 inch annually. With millions of acres of land susceptible to water and wind erosion, methods to overcome these losses are very vital. Therefore, much research has gone into solving this problem but much of this has been devoted to studying the measures that affect run-off with its subsequent nutrient and soil losses. These measures include level terracing, contour surface planting, contour listing, and more recently, mulch tillage methods. Unfortunately, not much has been done to relate erosion control measures to crop yields. It must also be strongly emphasized that complex interrelationships among factors and interactions of factors determine crop yields. Any yield prediction model which does not incorporate factors other than the one being studied is inadequate and incomplete. Though erosion control is possible through the manipulation of land cover, slope length, and degree of slope, the effects of these factors on soil losses depend on other controlled and uncontrolled factors such as management, environment, weather, and soil properties. In most of the erosion control studies, however, these other yield-influencing factors were either held constant or disregarded.