THE EFFECT OF SOIL THICKNESS ON CROP YIELDS

摘要

Data from several reclamation projects of non-prime, non-prime cropland, and prime farmland soil research projects are summarized. As one would expect, the soil thickness of reclaimed surface mined land had a significant effect on various crop yields. The soil thickness was most important for corn, followed by grain sorghum, soybeans, wheat, and alfalfa. Soil compaction also affected crop yields, especially for corn. Since the primary standard used to determine Phase III bond release in the mid-western states is based on corn yield, several studies were conducted on the effect of both soil depth and bulk density data as controlling factors in determining corn yield. Soybeans and wheat yields are less affected by soil depth than was found for corn. Alfalfa yield was least affected by soil depth and this crop helped reduce soil compaction. Corn yields were significantly improved following five years in alfalfa production. Yield data were collected on most areas as a part of continuing activities for at least ten years. Most of the corn, soybean, and wheat yields were collected with a combine equipped with a yield monitor. In many of these projects, subsoiling or ripping, liming, cropping practices prior to planting corn, and organic amendments to the subsoil prior to replacement of the topsoil were also variables that were evaluated as to their role in corn yield. Although these studies illustrated significant effects on corn yield, space does not allow them to be summarized here.