Quantifying improvements in water‐stable aggregation caused by corn stover retention

• Published in: Soil Science Society of America journal Vol. 85; no. 3; pp. 776 - 788
• Main Authors: Ojekanmi, Abimbola, Johnson, Jane M. F.
• Format: Journal Article
• Language: English
• Published: United States Alliance of Crop, Soil, and Environmental Science Societies 01-05-2021
• Subjects: Agriculture
• ISSN: 0361-5995; 1435-0661
• DOI: 10.1002/saj2.20198

Corn (Zea mays L.) stover harvest must be balanced against protecting soil properties, including water‐stable aggregates (WSA). The formation and maintenance of WSA functions of multiple factors including management. Harvesting stover alters the mass of the residue retained, which might alter a soil's ability to form and maintain WSA. A study was conducted on two independently replicated fields under chisel plow (CP) and no‐till (NT) management, both in a corn–soybean [Glycine max. (L.) Merr.] rotation with four corn residue retention treatments (RRT): [harvesting only grain, grain plus cobs, grain plus about half the stover, and grain plus as much stover as possible (Grain + Aggressive)], returning about 8, 5, 4 and 2 Mg ha−1 yr−1 dry stover, respectively. Water‐stable aggregates, their distribution, and mean weight diameter (MWD) were determined on a clay loam or loam Mollisol collected at 0 to 5 and 5 to 10 cm. Treatments, crop phase, soil depth, and their interactions were analyzed via a mixed linear model. Linear regression was used to assay the relationships between WSA and the average mass of residue returned. In both fields, Grain + Aggressive had the lowest WSA and MWD, and fewer ≥2‐mm aggregates than other RRTs and, in the NT field, fewer in the 1‐ to 2‐mm class size as well. Overall, WSA increased by 0.85 and 2.25% per Mg stover returned under CP and NT, respectively. Harvesting stover reduced the formation and/or the maintenance of WSA, thereby reducing their ability to resist the erosive force of water.