Assessing intervention effectiveness at promoting voluntary conservation practice adoption in agrienvironments.

While implementing conservation practices on private farms and forests can produce substantial environmental benefits, these practices are not being adopted widely enough to result in measurable improvements at regional scales. Researchers have investigated the production and program factors influencing producer choices to voluntarily adopt these practices. However, existing reviews have disagreed about many findings, raising questions about review methods, including omitted variable bias. Further, applying lessons from past work to promote adoption is difficult because many reviews have investigated dispositional or demographic variables that practitioners and policy-makers cannot directly observe or influence. We conducted a new review of 146 empirical studies that tested effects of different interventions on increasing the likelihood of producers adopting conservation practices, with the aim to produce robust and directly applicable findings. We developed a meta-regression of quantitative studies from diverse disciplines that filtered by study quality (i.e. use of randomization and clear analysis reporting), which we then synthesized with a thematic analysis of qualitative studies on producer perspectives about conservation practices. We find that, of the interventions assessed, financial incentives have the strongest evidence of increasing the likelihood that producers adopt conservation practices. However, this effect was only apparent after filtering by study quality, which also improved model fit and identified significant regional differences. The thematic review of qualitative studies revealed that peer groups may be successful in reinforcing adoption behaviors due to homophily effects and that financial incentives not only offset implementation costs but also mitigate perceived risks of adoption. Given problems we encountered in testing hypotheses about the magnitude of variability explained by intervention types and practice characteristics, we provide recommendations for future research, and particularly the need for additional experimental and longitudinal work to clarify relationships between program design and practice adoption rates. This article is protected by copyright. All rights reserved.