Optimization of reduced chemical fertilizer use in tea gardens based on the assessment of related environmental and economic benefits.

Chemical fertilizer application is the primary method used to maintain tea yield and quality, but has a negative environmental impact owing to its excessive use. This study sought to assess the environmental and economic benefits of three different chemical fertilizer reduction modes: Single reduction of chemical fertilizer (SRCF), combined application of organic and chemical fertilizer (CAOF), and controlled-release fertilizer substitute (CRFS). Differences in soil nutrient content, NP (NH4+-N, NO3-N and total P) runoff loss, tea yield and quality, and the revenue of tea planting across different fertilizer reduction treatments were then discussed. We also analyzed the coupling effects of these different fertilization modes, fertilization rate and time on soil NP runoff loss, which allowed us to determine the optimum fertilization method based on differences in their respective environmental and economic benefits. Our results revealed differences in soil nutrient content, tea yield and quality, NP runoff loss, and revenue owing to tea planting across the different fertilization treatments. Soil pH after fertilization was significantly lower than before fertilization. CAOF was beneficial and improved soil nutrients as well as tea yield and quality. Of the tested methods, 50% combined application of organic and chemical fertilizer (CAOF2) was the best, as it resulted in the best tea quality and yield. CAOF2 also had the highest revenue. In addition, it was beneficial in reducing NP runoff loss. CRFS was advantageous in its persistent fertilizer efficiency and reduction in NP runoff loss. With CAOF, NP runoff loss was primarily caused by quick-acting chemical fertilizer. With extended time, NP runoff loss caused by fertilization was gradually decreased. Given our analysis of the environmental and economic benefits of different fertilizer reduction methods, CAOF2 emerged in this study as the best fertilizer reduction treatment option.