Effect of Gypsum, Cover Crop, and Crop Rotation on Bulk Density and Aggregate Properties of Soils

Soybean production, worldwide, typically involves full tillage resulting in much less biomass than other crops, leading to decreased soil organic matter and increased soil degradation. The goal of this study was to evaluate the potential benefits of an innovative management system that includes the combinations of no-till, crop rotation, cover crop, and gypsum application on continuous soybean production. The response of soil physical properties, i.e. bulk density and water-stable aggregates, was evaluated across a range of soil types and climatic conditions. Treatments consisted of comparing (1) continuous soybean to a soybean-corn and corn-soybean rotation, (2) cereal rye [Secale cereale (L.)] cover crop to no cover crop, and (3) gypsum surface-applied at 0, 1.1, and 2.2 Mg ha-1. The study was replicated at four different sites in the United States, including Shorter (AL), Farmland (IN), Hoytville (OH), and Piketon (OH). At the end of the 5-year study, soil bulk density and aggregate stability were determined. Soil bulk density and water-stable aggregates were unaffected by gypsum addition regardless of the location. Including cereal rye as a winter cover increased soil aggregation and bulk density at the Hoytville location only. Rotating the soybeans with corn (compared to continuous soybeans) resulted in soil aggregation and bulk density improvements at all research locations. Results indicated that soybean production that included crop rotation into management system improved soil aggregate stability, whereas cover crop benefits were less effective and amending the soil with gypsum did not significantly affect these soil properties.