Effects of Soybeans on Soil Properties Related to Soil Erodibility1
- G. R. Bathke and
- G. R. Blake2
Research was conducted from 1980 to 1982 to examine the relationship between soybean (Glycine max L.) cropping and enhanced soil erodibility. Soil samples from the 1-to10-cm layer were taken from contiguous fields, cropped to soybeans and corn (Zea mays L.) the previous season, across Southern Minnesota in the spring of 1980 (1980 field survey) and the spring of 1982 (1982 field survey) and analyzed for their aggregation tendencies. In the 1980 field survey, aggregate size, stability, and carbon content were lower following soybeans than corn. The 1982 field survey indicated a reduced cloddiness in soybean fields when compared with corn fields by using a rapid field sieving test. Percent by weight of clods > 19 mm was less, and percent by weight of clods < 10 mm was greater following soybeans than corn. Field plots were established to study the soil-protecting effect which has been attributed to a soybean canopy. A soybean canopy was not effective in maintaining aggregate size or stability during the growing season over that of a bare soil. Leaving soybean residue on the soil surface during winter resulted in larger, more stable aggregates than plots with no cover or residues. A second set of field plots was designed to investigate the effects of a soybean or corn crop and combinations of surface residue conditions on soil properties. Aggregates were of equal size but significantly less stable after soybeans compared with corn when sampled in the fall. In the spring the aggregates were less stable at one location and of equal stability at two locations, but were smaller in size due to soybean cropping at all locations. Replacing soybean with corn residue during winter generally had no consistent significant effect on soil aggregation. This leads to the conclusion that there is an effect of the growing crops themselves, or of their root remains, or both on soil aggregates, but not attributable to above-ground residue differences between crops.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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