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Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 4/5/2013 Publication Date: 9/6/2013 Citation: Weyers, S.L., Johnson, J.M., Archer, D.W. 2013. Assessment of multiple management systems in the Upper Midwest. Agronomy Journal. 105:1665-1675. Interpretive Summary: Researchers at the North Central Soil Conservation Research Lab in Morris, MN, undertook a ten year evaluation of organic and conventional cropping systems. The experiment also involved comparisons of tillage, rotation and fertility strategies. Soil quality parameters were measured over time. Conservation approaches with reduced tillage and diverse crop rotations had the greatest impact on improving soil quality over time. Traditional approaches with conventional tillage and two-year corn-soybean rotations showed very little change over time and had the lowest soil quality. While there was no direct difference between conventional and organic management, this research establishes that conservation management strategies used within these management systems can improve soil quality. Scientists, land managers, and policy makers will benefit from this research when they need to develop management systems for both conventional and organic approaches to agriculture. Technical Abstract: Reduced tillage, multi-crop rotations and use of organic fertilizers are characteristically expected to improve soil quality. As measures of soil quality, microbial and soluble C and N were evaluated in an nine-year assessment of management practices alternative to a conventionally managed two-year corn-soybean rotation, in which reduced tillage, increased crop rotation diversity, and organic practices were utilized. Reducing tillage disturbance with a strip-tillage approach was the primary factor leading to improved soil quality. Organic versus conventional system-level management statistically increased microbial biomass N by the eighth crop rotation, but trends for increasing levels microbial biomass C and soluble C were apparent. A four-year over a two-year crop rotation significantly increased both microbial C and N and also soluble organic C and but not total soluble N. As expected, fertilizer application significantly increased all soil quality measures over a non-fertilized condition; however, there was little significant difference between organic and conventional fertilizers. Increased soil quality within the organic management system was consistent with the three-year transition requirement to obtain organic certification. Across organic and conventional management systems, improvement to soil quality may be more immediately observed with implementation of reduced tillage in combination with more diverse crop rotations. |
