When does no-till produce more? A global meta-analysis

Authors: PITTELKOW, CAMERON - University Of California; LINQUIST, BRUCE - University Of California; LUNDY, MARK - University Of California; LIANG, XINQIANG - Zhejiang University; VAN GROENIGEN, KEES JAN - Northern Arizona University; LEE, JUHWAN - Swiss Federal Institute Of Technology Zurich; VAN GESTEL, NATASJA - Northern Arizona University; SIX, JOHAN - Swiss Federal Institute Of Technology Zurich; Venterea, Rodney - Rod; VAN KESSEL, CHRIS - University Of California

Submitted to: Field Crops Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/19/2015
Publication Date: 8/14/2015
Publication URL: http://handle.nal.usda.gov/10113/61416
Citation: Pittelkow, C.M., Linquist, B.A., Lundy, M.E., Liang, X., Van Groenigen, K., Lee, J., Van Gestel, N., Six, J., Venterea, R.T., Van Kessel, C. 2015. When does no-till produce more? A global meta-analysis. Field Crops Research. 183:156-168.

Interpretive Summary: Feeding a growing world population while protecting environmental quality and enhancing the natural resource base represents a major challenge for agricultural research. No-till agriculture is a widely adopted management system with the aims of reducing soil erosion, decreasing input costs, and sustaining long-term productivity. However, the impacts of no-till on crop yields are variable and an improved understanding of the factors limiting productivity is needed to support evidence-based management decisions for no-till agriculture. We conducted a global meta-analysis to evaluate the influence of various crop and environmental variables on no-till yields using data obtained from peer-reviewed publications (678 studies with 6005 paired observations, representing 51 crops and 63 countries). Across all observations, no-till reduced yields by 5.1% compared to conventional tillage practices. Yields under no-till were not reduced for oilseeds, cotton or legume crops but were reduced most for root crops (-21.4%). Considering cereals, the negative impacts of no-till were smallest for wheat (-2.6%) and largest for rice (-7.5%) and maize (-7.6%). By region, no-till reduced yields the most in tropical latitudes (-15.1%) and the least in temperate latitudes (-3.4%). Among the variables considered in our analysis, the most important factors influencing the overall yield response were aridity index, no-till duration, and N rate. No-till performed best under rainfed conditions in dry climates, with yields often being equal to or higher than conventional tillage practices. Yields in the first few years following no-till implementation declined for all crops except oilseeds and cotton. With the exception of maize, no-till yields matched conventional till yields after 3 to 10 years. Across all observations, yields under no-till were reduced by 12% without any N fertilizer addition and by 4% with inorganic N fertilizer addition. In humid climates, overall yield reductions without N addition were more severe (-22%). Our results indicate that no-till yield outcomes are highly dependent on region, climate, crop type, and N inputs. The fact that yield reductions occurred in a number of cases suggests that improved targeting and adaptation of no-till is necessary to contribute to food production and agricultural development goals, particularly for maize grown in tropical latitudes where access to N inputs may be limited. While recognizing that no-till has important benefits aside from yield, our results identify factors contributing to no-till yield gaps and provide an improved framework for conducting trade-off analyses, thereby supporting no-till crop management and international development strategies based on available scientific evidence. These results will be of interest to producers, policy-makers, and scientists interested in promoting agricultural practices that enhance crop and food production while protecting environmental quality.

Technical Abstract: Feeding a growing world population while protecting environmental quality and enhancing the natural resource base represents a major challenge for the agricultural research and development community. No-till agriculture is a widely adopted management system with the aims of reducing soil erosion, decreasing input costs, and sustaining long-term productivity. However, the impacts of no-till on crop yields are variable and an improved understanding of the factors limiting productivity is needed to support evidence-based management decisions for no-till agriculture. We conducted a global meta-analysis to evaluate the influence of various crop and environmental variables on no-till yields using data obtained from peer-reviewed publications (678 studies with 6005 paired observations, representing 51 crops and 63 countries). Across all observations, no-till reduced yields by 5.1% compared to conventional tillage practices. Yields under no-till were not reduced for oilseeds, cotton or legume crops but were reduced most for root crops (-21.4%). Considering cereals, the negative impacts of no-till were smallest for wheat (-2.6%) and largest for rice (-7.5%) and maize (-7.6%). By region, no-till reduced yields the most in tropical latitudes (-15.1%) and the least in temperate latitudes (-3.4%). Among the variables considered in our analysis, the most important factors influencing the overall yield response were aridity index, no-till duration, and N rate. No-till performed best under rainfed conditions in dry climates, with yields often being equal to or higher than conventional tillage practices. Yields in the first few years following no-till implementation declined for all crops except oilseeds and cotton. With the exception of maize, no-till yields matched conventional till yields after 3 to 10 years. Across all observations, yields under no-till were reduced by 12% without any N fertilizer addition and by 4% with inorganic N fertilizer addition. In humid climates, overall yield reductions without N addition were more severe (-22%). Our results indicate that no-till yield outcomes are highly dependent on region, climate, crop type, and N inputs. The fact that yield reductions occurred in a number of cases suggests that improved targeting and adaptation of no-till is necessary to contribute to food production and agricultural development goals, particularly for maize grown in tropical latitudes where access to N inputs may be limited. While recognizing that no-till has important benefits aside from yield, our results identify factors contributing to no-till yield gaps and provide an improved framework for conducting trade-off analyses, thereby supporting no-till crop management and international development strategies based on available scientific evidence.