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 (lm). 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.
Bibliographical noteFunding Information:
We gratefully acknowledge Mr. Fynboh, Mr. Hallman and Mr. Erdman for graciously allowing us to conduct research on their farms. G. Amundson, and C. Rollofson for their assistance and analytical support collecting, processing, and analyzing soil, and plant samples; J. Hanson for his analytical support for chemical analyses of soil and plant samples; C. Hennen, and S. Larson for their assistance in plot maintenance; B. Burmeister and J. Zaharick for proof-reading the revised manuscript; and the reviewers and Associate Editor for their careful, thoughtful and courteous review. The use of trade, firm, or corporation names in this publication is for the information and convenience of the reader. Such use does not constitute an official endorsement or approval by the United States Department of Agriculture or the Agricultural Research Service of any product or service to the exclusion of others that may be suitable. The USDA is an equal opportunity provider and employer. This publication is based on research supported by the USDA-Agricultural Research Service-REAP Project and by funding from the customer-supported XCEL Energy Renewable Development Fund. This report was prepared as a result of work sponsored by funding from the customer-supported XCEL Energy Renewable Development Fund administered by NSP. It does not necessarily represent the view of NSP, its employees, nor the Renewable Development Fund Board. NSP, its employees, contractors, and subcontractors make no warranty, express or implied and assume no legal liability for the information in this report; nor does any party represent that the use of this information will not infringe upon privately owned rights. This report has not been approved or disapproved by NSP nor has NSP passed upon the accuracy or adequacy of the information in this report.
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