The Impact of the Rural-Urban Migration of Chinese Farmers on the Use of Rural Homesteads: A Threshold Model Analysis

China's urbanisation process is unique compared to that of other developed economies in that while the rural population is migrating to the cities in large numbers, the area of rural homestead use also continues to increase. This research uses macro data and a threshold model to further analyse this phenomenon of "farmers leaving while rural homestead increasing". Specifically, we focus on the mechanisms of action, development patterns and regional differences in the impact of the rate of rural-urban migration (RRUM) on the rate of increase in the area of rural homesteads (IARH), and discuss the spatial spillover effects of the impact between the two. The results of the research show that: (1) There is an "inverted U-shaped" double threshold effect on the impact of RRUM on IARH. (2) Rural population density and regional urban-rural income disparity are used as threshold variables, respectively, resulting in a sudden change in the relationship between RRUM and IARH. (3) The threshold effect of RRUM on IARH mainly exists in the central and western regions, non-minority nationality areas, non-provincial capital cities and non-resource-based cities. (4) The RRUM can not only directly affect the local IARH, but also indirectly affect the surrounding areas through spatial spillover effects. Our research provides critical insights for policy makers on the reform of the rural homestead system and urbanisation development strategies in different regions.