Stover harvest impacts soil and hydrologic properties on three Minnesota farms

Authors: Johnson, Jane; STROCK, JEFFREY - University Of Minnesota; Barbour, Nancy; TALLAKSEN, JOEL - University Of Minnesota; REESE, MIKE - University Of Minnesota

Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/30/2017
Publication Date: 6/5/2017
Publication URL: http://handle.nal.usda.gov/10113/5700742
Citation: Johnson, J.M., Strock, J.S., Barbour, N.W., Tallaksen, J.E., Reese, M. 2017. Stover harvest impacts soil and hydrologic properties on three Minnesota farms. Soil Science Society of America Journal. 81:932-944. https://doi.org/10.2136/sssaj2017.01.0007

Interpretive Summary: After harvesting corn grain, the material left behind such as the corn cobs, stalk and leaves is called stover. Corn cobs and stover material may be used as animal bedding or even as material for making liquid fuels such as ethanol, or used to produce electricity. Another important use of stover is to cover the soil to protect it from wind and water. Wind and water on naked soil can move high quality soil form the field to ditches, water ways or into the air causing air or water quality issues. Another important job for corn stover and cobs is to decompose, feeding soil organisms and helping build healthy soils. We worked with producers on three farms to see what would happen to their soils if just grain, grain and cobs or grain and about half the stover were harvested. We found that the best combination for the soil health was to keep the stover in the field and to limit the tillage.

Technical 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.