The global demand for food and the degradation of natural resources necessitate a shift towards more sustainable agricultural practices. Environmental sustainability in agriculture involves responsible stewardship of natural systems and resources. Sustainable agricultural practices, encompassing crop rotation, cover cropping, integrated pest management, and agroforestry, aim to enhance environmental sustainability while maintaining or improving farm productivity. The adoption of these practices often requires incentives, farmer effort, and government/public-private partnerships. However, adoption is influenced by various factors, including program conditions, incentives offered, farmer preferences, economic conditions, and cultural characteristics. This scoping review systematically evaluates the evidence on the effects of incentives offered to farmers to adopt sustainable agricultural practices, examining nearly 18,000 papers across diverse incentive types offered by various actors.

The review systematically examined existing literature focusing on incentives for sustainable agricultural practices and their impact on various outcomes. It explored the diverse range of incentives used, including market-based (subsidies, payments), non-market-based (technical support, technology transfer), regulatory measures (environmental laws, standards), and cross-compliance incentives (payments conditional on adherence to standards). The review also analyzed the relationship between the adoption of sustainable practices and environmental, productivity, and economic outcomes. The existing research was assessed to understand the gaps and provide recommendations for future research.

This scoping review followed the PRISMA-SCR guidelines. A three-phase screening process (title, abstract, full-text) was conducted on 17,936 articles. Inclusion criteria focused on studies published since 1994 explicitly addressing incentives for sustainable agricultural practices, their adoption, and the link between adoption and sustainability outcomes. A machine learning-based approach helped identify and cluster common terms and topics. A stratified random sample of 99 articles (93 included after language/availability checks) underwent in-depth review and data extraction. Data extraction documented incentive types, farmers' adoption behaviors, and corresponding outcomes. An evidence assessment was carried out based on the clarity of the research question, justification of the approach, methodology description, and robustness. Each article was scored 1-5, with higher scores indicating stronger evidence and methodology. The analysis explored the relationships between incentives, adoption, and outcomes across various incentive categories (market-based, non-market-based, regulatory, cross-compliance) and outcome types (environmental, productivity, economic).

The review revealed that irrespective of the incentive type, programs offering short-term economic benefits had higher adoption rates compared to those focused solely on ecological services. Long-term adoption was strongly linked to perceived positive impacts on farms or the environment. Technical assistance and extension services significantly enhanced adoption rates across all incentive mechanisms. Market and non-market incentives were the most prevalent, while all three incentive categories were used relatively uniformly to achieve environmental outcomes. Profitability outcomes often required balanced incentive structures, while productivity outcomes leaned towards market and non-market incentives. The quality of evidence linking incentives to outcomes varied, with stronger evidence supporting the link between cross-compliance incentives and environmental outcomes, and between market/non-market incentives and profitability-related outcomes. Regulatory approaches were less frequently documented but generally had strong methodologies. A significant gap existed in measuring environmental outcomes, mostly relying on qualitative assessments of farmer perceptions rather than robust quantitative data. The study highlighted a scarcity of randomized controlled trials, hindering the establishment of causal relationships between incentives, adoption, and outcomes. The review also found that multipronged interventions, combining various incentive types and addressing multiple outcomes, were relatively common and successful. Contextual factors (farmer characteristics, biophysical conditions, institutional context, market trends) significantly influenced adoption decisions. The effectiveness of incentives and the likelihood of adoption varied across agricultural practices and predicted outcomes.

The findings underscore the importance of designing incentive programs that balance short-term economic benefits with long-term environmental goals. The crucial role of technical assistance and extension services highlights the need for integrated approaches that combine financial incentives with capacity building and knowledge transfer. The variation in evidence quality across different incentive types and outcomes emphasizes the need for more rigorous quantitative studies, particularly randomized controlled trials, to establish robust causal relationships. The study's findings inform the design of effective sustainable agricultural policies by emphasizing the need to tailor incentives to the specific context, considering trade-offs among different outcomes and acknowledging the influence of various contextual factors.

This scoping review provides valuable insights into the effectiveness of diverse incentive mechanisms in promoting sustainable agricultural practices. The results highlight the need for integrated, context-specific approaches that combine economic incentives with technical assistance and address both short-term economic and long-term environmental goals. Future research should focus on robust quantitative studies, especially randomized controlled trials, to strengthen the evidence base and improve the understanding of causal pathways. Further investigation is needed into the effectiveness of regulatory approaches and the long-term sustainability of outcomes.

The review's reliance on existing literature introduces inherent limitations related to publication bias and potential variations in study quality and methodology. The scoping review's breadth limits the depth of analysis of individual studies. The evidence assessment was subjective, introducing potential bias. The lack of randomized controlled trials hinders the ability to definitively establish causal relationships between incentives, adoption, and outcomes. Data on environmental outcomes were predominantly qualitative, limiting the scope of quantitative analysis.