Effects of Soybean and Corn Residue Decomposition on Soil Strength and Splash Detachment
1987
Gantzer, C. J. | Buyanovsky, G. A. | Alberts, E. E. | Remley, P. A.
Although field experiments have documented increased soil and water losses after soybeans (Glycine max L.) as compared with corn (Zea mays L.), a “soil effect” appears to be nondetectable by regular laboratory means. Because significant differences in quantity and quality of post-harvest residues occur between soybean and corn, a laboratory incubation experiment was designed to assess the effect of the plant materials on soil properties. Analysis shows that laboratory incubation of disturbed soil with and without corn and soybean residues at 20°C, with optimal water contents of 25% v/v, decreases splash detachment, increases shear strength and aggregate size after 7 to 14 d. Additions of corn or soybean residues increase soil strength and decrease soil splash in a log-linear fashion. The most pronounced effects were observed after 14 d. This corresponds to peak microbiological activity, indicating changes in stability are probably related to biological processes. Corn residue at typical field rates (20 Mg/ha) reduced soil splash by about one-third and increased strength about two times as compared to the check after 14 d of incubation. Incubation with soybean residue for a similar time caused slightly greater soil splash than incubation with the same amount of corn residue, suggesting that small changes in stability are related to residue quality. No difference in soil strength relative to residue quality was detected after 14 d of incubation, indicating a subtle difference between splash and strength as measures of surface-soil stability. Aggregate size measurements were less sensitive to plant residue treatment and time of incubation than splash or strength.
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