Bridging Knowledge and Action: An Integrated TPB-OST Framework for Understanding Farmers’ Sustainable Agricultural Practices in Poyang Lake, China

Promoting farmers’ adoption of sustainable agricultural practices is essential for advancing agricultural green transformation and ecological conservation in the Poyang Lake Basin. Current research frequently relies on a single theoretical perspective and insufficiently reveals the synergistic mechanism linking knowledge conversion, psychological cognition, and institutional support. This study integrates the Theory of Planned Behavior (TPB) and Organizational Support Theory (OST) to construct a holistic “knowledge–psychology–behavior–institution” analytical framework. Based on a questionnaire survey of 485 farmers from 12 districts and counties surrounding Poyang Lake, we use structural equation modeling and the Process macro to examine direct effects, mediating effects, and the moderating role of government support. The results show that sustainable knowledge sharing and application significantly improve farmers’ behavioral intention through attitude, subjective norms, and perceived behavioral control, thereby positively promoting actual sustainable practices. Government support plays a significant positive moderating role in the translation of knowledge and psychological factors into behavioral intention. This study enriches the theoretical interpretation of farmers’ pro-environmental behavior from the synergistic perspective of individual cognition and external institutional constraints. The findings provide empirical support for local governments to optimize agricultural extension services, improve policy support systems, and promote coordinated development between ecological protection and high-quality agriculture.