A regionally-adapted implementation of conservation agriculture delivers rapid improvements to soil properties associated with crop yield stability

Authors: WILLIAMS, A - University Of Minnesota; JORDAN, NICHOLAS - University Of Minnesota; SMITH, RICHARD - University Of New Hampshire; HUNTER, M - Pennsylvania State University; KAMMERER, D - Pennsylvania State University; KANE, R - Michigan State University; KOIDE, ROGER - Brigham Young University; Davis, Adam

Submitted to: Scientific Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/21/2018
Publication Date: 5/30/2018
Citation: Williams, A., Jordan, N.R., Smith, R.G., Hunter, M.A., Kammerer, D.A., Kane, R.T., Koide, R.T., Davis, A.S. 2018. A regionally-adapted implementation of conservation agriculture delivers rapid improvements to soil properties associated with crop yield stability. Scientific Reports. 8:8467.

Interpretive Summary: Conservation agriculture is an agroecosystem management system that may enhance climate resilience. However, we hypothesize that conservation agriculture incurs a yield tradeoff unless full implementation of all key elements is achieved, i.e., reduced tillage intensity, sustained soil cover via crop residues or cover crops, and increased crop rotational diversity. Across four US states, we assessed soybean and maize yield stability, and soil factors expected to mediate resilience, in uniform and zonally-managed conservation agriculture systems that varied in tillage intensity, cover cropping, and fertility management. Yield stability was quantified along two dimensions: minimum yield potential and temporal yield variability. Structural equation modeling revealed that soybean temporal yield variability was strongly related to soil cation exchange capacity, which was driven by improvements in soil organic matter as a result of cover cropping. Nitrogen fertilization played a critical role in improving maize minimum yield potential. Changes to soil moisture retention as a result of reduced tillage intensity were unrelated to crop yield stability. Our results show that conservation agriculture may play an important role in the development of climate-resilient agricultural systems that are also high yielding.

Technical Abstract: Climate models predict increasing growing-season weather variability, with negative consequences for crop production. Maintaining agricultural productivity despite variability in weather (i.e., crop yield stability) will be critical to meeting growing global demand. Conservation agriculture is an agroecosystem management system that may enhance climate resilience. However, we hypothesize that conservation agriculture incurs a yield tradeoff unless full implementation of all key elements is achieved, i.e., reduced tillage intensity, sustained soil cover via crop residues or cover crops, and increased crop rotational diversity. Across four US states, we assessed soybean and maize yield stability, and soil factors expected to mediate resilience, in uniform and zonally-managed conservation agriculture systems that varied in tillage intensity, cover cropping, and fertility management. Yield stability was quantified along two dimensions: minimum yield potential and temporal yield variability. Structural equation modeling revealed that soybean temporal yield variability was strongly related to soil cation exchange capacity, which was driven by improvements in soil organic matter as a result of cover cropping. Nitrogen fertilization played a critical role in improving maize minimum yield potential. Changes to soil moisture retention as a result of reduced tillage intensity were unrelated to crop yield stability. Our results show that in contrast to crop yields, implementation of all key conservation agriculture elements is not necessary to improve maize and soybean yield stability; rather, individual factors relating to soil fertility are more important. In addition, the individual elements that improved crop yield stability had no negative impact on crop yields, suggesting that conservation agriculture may play an important role in the development of climate-resilient agricultural systems.