Abstract: Achieving green agricultural production depends on changes in smallholder farmers’ production methods. Compared with previous studies that focused on manual fertilizer application, this study focused on the effect of machinery use and use links on fertilizer application and uniformity among farmers. Using data from the 2017 China Rural Household Panel Survey (CRHPS), the impact of agricultural mechanization on fertilizer application in wheat was explored through ordinary least squares (OLS) method, as well as treatment effect models, with attention to differences in fertilizer application across sources of machinery use. The results show that the use of machinery does not reduce fertilizer use in wheat but can reduce inter-farmer fertilizer application differences. Only machine sowing decreased fertilizer application and uniformity, mostly because wheat has a higher fertilizer application rate at sowing. After separating the various sources of farm machinery use, it is discovered that using machinery services rather than buying machinery equipment reduces the amount of fertilizer applied per hectare by 150.45 kg, and increases fertilizer uniformity. For instance, compared with purchasing machine equipment, the purchase of machine services lowered fertilizer application by 213.45 kg per hectare and increased fertilizer application uniformity by 0.32 units per hectare during seeding. Additionally, farmers can cut their fertilizer input by 283.95 ¥∙hm⁻² by adopting machine sowing. Purchasing machinery services can lower fertilizer input by 394.50 ¥∙hm⁻², especially during seeding the input was decreased by 352.80 ¥∙hm⁻². This suggests that agricultural mechanization can achieve fertilizer reduction and reduce inequality in fertilizer application among farmers, mainly through outsourcing. The findings of this study can help expand our understanding of the relationship between agricultural mechanization and modern agriculture and can also provide strong support for the green transformation and sustainable development of agriculture in China.