Stover Harvest Impacts Soil and Hydrologic Properties on Three Minnesota Farms

Abstract

Stover is the material remaining after harvesting corn (Zea Mays L.) grain, which may be removed for a variety of purposes, but these material are also crucial for protecting and enriching soil properties. This research was conducted on-farm in collaboration to assess the impact of harvesting cobs (Grain+Cob), and/or all stover (Grain+Stover) in addition to grain (Grain) on several soil properties related to soil health: soil organic carbon (SOC), particulate organic matter – carbon (POM-C), dry aggregate size distribution (DASD), fraction of aggregate class remaining stable in water (ASW) and unconfined field soil hydraulic properties including infiltration rate (i), sorptivity (S) and characteristic mean pore size (lm). The farms had different crop rotation, tillage practices and soil textures. The Donnelly farm, on a Hamerly clay loam, was managed in corn/soybean (Glycine Max L. [Merr.]) rotation with minimal tillage. The Clontarf farm, on a Malachy sandy loam, was managed in corn/edible bean (Phaseolus vulgaris L.) rotation with aggressive tillage. The Chokio farm, on Hamerly clay loam, was managed in corn/soybean/wheat (Triticum aestivum L.) rotation and aggressive tillage. The fields managed with aggressive tillage displayed evidence of degrading SOC, DASD and hydraulic properties. The field managed with minimal disturbance, the Grain treatment maintained SOC throughout the profile, and had favorable DASD and hydrologic properties, but harvesting residues undermined these positive attributes. Based on farms in order to sustain measure soil properties, it was necessary to return >9 Mg stover ha-1 stover when aggressively tilling and >5.6 Mg stover ha-1 with reduced tillage.