Novel oilseed crops improved soil dry aggregate size distribution implying increased erosion resilience

Abstract

Adoption of oilseeds is expanding in the United States Corn Belt, but their influence on soil aggregation, an indicator for susceptibility to surface wind or water erosion, is scarce. Soil physical properties were measured in rotation treatments of two seasonally different rotation systems: (1) winter oilseeds versus winter fallow and (2) summer oilseeds versus corn (Zea mays L.). Soil was collected from the top 5 cm of both rotations in the fall, following soybean (Glycine max L.) harvest, and separated into six dry aggregate size distribution (DASD) fractions used to calculate the mean weight diameter (MWD), the wind erodible fraction (WEF; 0–1.0 mm aggregates), and the ability of aggregates to remain stable in water (ASW; 1–2 and 2-3-mm aggregates). Winter camelina (Camelina sativa L.) had a lower WEF (0.22 ± 0.029) compared to winter fallow (0.26 ± 0.029). Summer oilseed treatments had a significant influence on DASD with >50% of aggregates >2 mm in the summer oilseed treatments and >50% of aggregates >3 mm in the corn treatment. The corn–soybean, Calendula officinalis L.–soybean, and Brassica napas L.–soybean rotations did not differ significantly in MWD (3.59, 3.44, and 3.45, respectively) or WEF (0.20, 0.12, and 0.22, respectively) but had lower MWD and WEF than the Cuphea viscosissima Jacq. × Cuphea lancelota W.T. Aiton-soybean, Echium plantagineaum L.--soybean, and soybean–soybean rotations (MWD: 3.19, 3.23, and 3.22 and WEF: 0.28, 0.26, and 0.25, respectively). Neither winter nor summer oilseeds altered ASW. Nevertheless, MWD and WEF shifts indicate that oilseed crops improved soil aggregation and soil susceptibility to erosive forces of wind.