How does agricultural production outsourcing services affect chemical fertilizer use under topographic constraints: a farm-level analysis of China.

Agricultural production outsourcing services (APOS) are an important means to promote green and low-carbon development of agriculture in China. Topography is the key factor limiting the development of APOS. There is little research on the influence relationship between APOS and farmers' chemical fertilizer use from the perspective of topography. Based on the theory of economies of scale, this study empirically evaluated the effect of APOS on chemical fertilizer use and their differences from the perspective of nutrient elements under different topographic conditions by using micro survey data for farmers in China and econometric methods. The results show that APOS can reduce farmers' chemical fertilizer use, and this effect is more obvious for farmers with large farmland sizes and high education levels. Farmland topography directly affects the fertilizer reduction effect of APOS in China. Compared with plain areas, hilly and mountainous areas weaken this effect. To enhance the fertilizer reduction effect of APOS, China should fully consider farmland topography when promoting APOS development. In plain areas, farmland scale management should be further encourage to better utilize APOS as a means of reducing chemical fertilizer use. In hilly and mountainous areas, high-standard farmland construction and small agricultural machinery use can alleviate the constraints of topographical on the scale expansion of APOS. It is necessary to fully consider the differences in farmers' resource endowments and their awareness of purchasing agricultural services in promoting APOS development, especially in regard to the farmers with small farmland sizes and low education levels.