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

<title>Abstract</title> 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.100g^-1) and ley-arable rotations (0.05 g C.100^-1g per year 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. While future work should evaluate the net greenhouse gas emission implications of each practice and investigate the potential for synergistic effects if RA practices are adopted in combination, our results give land managers and policy makers confidence to further adopt these practices without loss of crop yield.