Social Network Centrality and Fertilizer Reduction: Evidence from a 14-Year Panel Study of Smallholder Farmers in Northwest China

Excessive fertilizer use not only harms agricultural sustainability but also leads to massive energy waste and carbon emissions. Under China’s carbon peaking and carbon neutrality goals, using social networks to spread better fertilization practices and reduce excessive application can deliver real wins for both energy savings and emission cuts. This paper examines whether farmers’ social network positions affect their fertilizer use. We analyze 14 years of data from 206 farm households in Gansu, China, using fixed effects models that incorporate degree, betweenness, and closeness centrality. Our results reveal that centrally positioned farmers substantially reduce fertilizer application: each 0.1 unit rise in standardized degree, betweenness, and closeness centrality corresponds to reductions of 1.26%, 0.84%, and 0.78%, which translate to actual reductions and carbon emission reduction of 1.06, 0.71, and 0.66 kg/mu; 9.52, 6.38, and 5.93 kg CO2e/mu. The effects are stronger for farmers with more education, higher off-farm income, and tighter network connections. The effect of degree centrality on fertilizer reduction increased by 7.2 percentage points after 2018. Extension services should build on existing social networks and use key node farmers to drive other farmers in the village to reduce fertilizer use. It helps reduce carbon emissions from fertilizer production and promote sustainable agricultural development.