Stover Harvest Impacts Soil and Hydrologic Properties on Three Minnesota Farms.

Stover, the material remaining after harvesting corn (Zea mays L.) grain, may be removed for many purposes, but this material is also crucial for protecting and enriching soil properties. This research was conducted on sites located on working farms to assess the impact of three levels of harvest: (i) Grain only, (ii) Grain+Cob and (iii) grain and all stover, which includes cobs (Grain+Stover) on several soil properties related to soil organic carbon (SOC) pools, dry aggregate-size distribution (DASD), fraction of dry aggregates remaining stable in water (ASW) and unconfined field soil hydraulic properties including infiltration rate (i), sorptivity (S) and characteristic mean pore size (λm). The Chokio site on a clay loam soil was managed in a corn/soybean (Glycine max L. [Merr.])/wheat (Triticum aestivum L.) rotation with chisel plow tillage to 18 cm. The Clontarf site on a sandy loam soil was managed in a corn/bean (Phaseolus vulgaris L.) rotation with deep disk tillage to 36 cm. The Donnelly site on a clay loam soil, was managed in a corn/soybean rotation with strip tillage to ⩽13 cm. At the Chokio and Clontarf sites, managed with 18- or 36-cm tillage, respectively, SOC, DASD and hydraulic properties decreased over time in all treatments. At the Donnelly site managed with <13-cm tillage, the Grain treatment maintained SOC throughout the profile, favorable DASD and hydrologic properties, but harvesting cobs or all stover undermined these positive attributes. Results of this study suggested that to protect soil properties from degradation all stover needs to be returned. [ABSTRACT FROM AUTHOR]