Submitted to: Renewable Agriculture and Food Systems
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/10/2017
Publication Date: 4/11/2017
Publication URL: http://handle.nal.usda.gov/10113/5700741
Citation: Weyers, S.L., Archer, D.W., Forcella, F., Gesch, R.W., Johnson, J.M. 2017. Can reducing tillage and increasing crop diversity benefit grain and forage production? Renewable Agriculture and Food Systems. doi: 10.1017/S1742170517000187.
Interpretive Summary: Researchers at the North Central Soil Conservation Research Lab in Morris, MN, and Northern Great Plains Research Laboratory in Mandan, ND, undertook an eight-year evaluation of conventional and alternative cropping systems. The experiment involved comparisons of tillage, rotation and fertility strategies. Crop yields, weed seed densities and system performance were evaluated over time. Overall system performance was best with conventional tillage and a two-year rotation due to higher corn grain yields. However, strip-tillage and diverse crop rotations had little impact on yields of soybean, wheat or alfalfa. Instability in corn grain prices, recognized soil health benefits of strip-tillage, and reduced economic risk with diverse cropping practices indicate potential for adoption of these practices. Scientists, land managers, and policy makers will be able to use this research to develop and promote conservation management strategies for agricultural production.
Technical Abstract: Benefits of reduced tillage and diverse rotation cropping systems include reversing soil C loss, mitigating greenhouse gas production, and improving soil health. However, adoption of these strategies is lagging, particularly in the upper Midwest, due to a perception that reduced tillage reduces crop yields. Therefore, an eight-year comparison of these conservation systems to a conventional system was conducted to evaluate effects on yields, weed seed densities and system performance measured with potential gross returns. This study compared conventional tillage (moldboard plow + chisel till, CT) to reduced tillage (strip-tillage + no-tillage, ST), each with a two-year (2y) or four-year (4y) crop rotation, abbreviated as CT-2y, CT-4y, ST-2y, and ST-4y. The 2y rotation was corn (Zea mays L.) and soybean (Glycine max ([L.).] Merr.); the 4y rotation was corn, soybean, wheat (Triticum aestivum L.) underseeded with alfalfa (Medicago sativa L.), and alfalfa. Only corn grain was significantly influenced by tillage strategy; CT systems yielded more than ST systems, regardless of rotation. Soybean grain yields were similar among CT-2y, CT-4y, and ST-4y, and lowest in the ST-2y. Yields of wheat and alfalfa were the same under both tillage strategies. Weed seed densities were higher in wheat and alfalfa, followed by corn then soybean, but were not influenced by tillage or rotation, nor negatively correlated to yield. Overall system performance, measured by potential gross returns, was highest in CT-2y and the same among the other systems, CT-4y, ST-4y, and ST-2y. However, within four out of eight years performance was the same among all four systems, indicating potential beneficial aspects of reduced tillage and diverse rotations. The data supports the need for more research on alternating or rotating tillage strategies with respect to crops in the rotation.