Temperate Regenerative Agriculture practices increase soil carbon but not crop yield-a meta-analysis

Regenerative Agriculture (RA) claims to build soil organic carbon (SOC) and increase crop yields through simultaneous adoption of a suite of management practices which restore soil health. However, this claim is largely unevidenced as few studies of fully integrated regenerative systems are currently available. As a first step to addressing this knowledge gap, we here examine three practices now being promoted as part of RA: reducing tillage intensity, cover cropping and including a grass-based phase in arable rotations (ley-arable rotations). Our Bayesian meta-analysis of 195 paired SOC and crop yield observations from a systematic review of published studies finds statistically significant increases in SOC concentration for reduced tillage intensity (0.06 g C center dot 100 g(-1)) and ley-arable rotations (0.05 g C center dot 100(-1) g yr(-1) of ley) compared to conventional practice over an average study duration of 15 years, but no effect of cover crops. None of these practices reduce yield during cropping years, although we find no evidence of a win-win between increasing SOC and enhanced agricultural productivity following adoption. Future work should also evaluate the net greenhouse gas emission implications of each practice and potential for synergistic effects if RA practices are adopted in combination. Nevertheless, our results suggest that the RA practices investigated here can be promoted by land managers and policy makers without crop yield losses.