Corn Residue Effect on the Yield of Corn and Soybean Grown in Rotation

Abstract Crop rotation provides a yield benefit that persists at optimal management levels. The exact reason for the rotation effect is unknown. One theory is that a given crop's own residue has an autoinhibitory effect when that crop is maintained under monoculture, and/or that residues of alternate crops have a stimulatory effect on one another under rotation. We conducted field studies at Lamberton, Rosemount, and Waseca, MN to test this theory. Soils at these locations are: Webster clay loam (fine‐loamy, mixed mesic Typic Haplaquolls), Waukegan silt loam (fine‐silty, over sandy, mixed, mesic Typic Hapludolls), and NicoIIet clay loam (fine‐loamy, mixed, mesic Aqnic Hapludolls), respectively. A series of 3‐yr crop sequences were established at each site. In the first year the experimental area was kept fallow. In the second year half of each replicated plot was planted to corn (Zea mays L.) and half to soybean (Glycine max (L.) Merr.) After grain harvest all above‐ground corn residue was removed from half of the corn area and transferred to half of the soybean area. All plots were then moldboard plowed. In the spring of the third year all plots were disked and planted uniformly in corn (1981, 1982) or soybean (1983, 1984). There was a significant effect of previous crop (rotation effect) on the yield of both corn and soybean, but the removal or addition of corn residue had no effect on the yield of either crop. This indicates that the yield response of corn and soybean to rotation is not due to beneficial or negative effects of decomposing above‐ground residue.