Part-time farming and cultivated land quality protection among large-scale farmers: a U-shaped relationship—evidence from China

Introduction Promoting farmers’ adoption of cultivated land quality protection practices is essential for long-term food security. This study develops a decision-making framework to examine how part-time farming affects the land protection behavior of large-scale farmers through three key production factors: land, capital, and labor. Methods Using survey data from 532 large-scale farming households in Jiangxi Province, China, this study applies ordinary least squares (OLS) and two-stage least squares (2SLS) models to estimate the linear and nonlinear effects of part-time farming on cultivated land quality protection practices. It further investigates the underlying mechanisms and examines heterogeneity by off-farm employment duration, exposure to natural disasters, geographical location, and dependence on rice income. Results and discussion The results reveal a significant U-shaped relationship between the degree of part-time farming and cultivated land quality protection behavior, with a turning point at an off-farm income share of approximately 52.5%. Part-time farming initially discourages land protection by reducing agricultural labor input and the scale of land operation, particularly during the early stage of off-farm employment. As the degree of part-time farming increases, however, agricultural socialized services and expanded social networks facilitate the adoption of land protection practices. These effects are more pronounced among farmers who engage in off-farm work for more than six months, operate farmland with a disaster-affected share exceeding 15%, or reside within 20 kilometers of a county town. Among farmers who derive a larger share of their income from rice production, the initial inhibitory effect is weaker and the turning point occurs earlier. The findings suggest that land quality protection policies should account for regional economic conditions, climatic risks, and geographical accessibility. Policy measures should promote agricultural socialized services, encourage appropriately scaled farm operations, develop digital platforms for sharing agricultural information, and strengthen rural infrastructure and disaster prevention systems.