Chemical fertilizer pollution control using drip fertigation for conservation of water quality in Danjiangkou Reservoir

The use of drip fertigation to reduce fertilizer pollution of the Danjiangkou Reservoir of China was explored. Specifically, a 4-year experiment was conducted to identify the optimum fertilizer rate for fertigation of a tea plantation. The treatments included five fertigation levels, 10 % (10 % NPK), 20 % (20 % NPK), 30 % (30 % NPK), 40 % (40 % NPK) and 50 % (50 % NPK) of the traditional fertilizer dose, and the traditional fertilizer dose under rain-fed conditions as a control (CK). Relative to CK, fertigation treatments decreased total nitrogen (TN), total phosphorus (TP) runoff loss (kg ha^-1) and TN and TP concentrations (mg kg^-1) in leaching water by 51.9-70.8, 51.7-67.5, 56.1-85.4, and 39.1-56.5 %, respectively. Total N, TP runoff loss and TN concentrations in leaching water generally increased with increasing fertilization rate among fertigation treatments; however, there was no significant difference in TP concentrations of leaching water. Yield increased with increasing rate of fertilization among fertigation treatments. The yields of the 30-50 % NPK treatments were similar (P > 0.05), but higher (P < 0.05) than those of the 10-20 % NPK treatments. There were no significant differences in yield among the 30 % NPK, 40 % NPK and CK treatments. The relative yields increased rapidly when the relative fertilizer rate was between 10 and 33 %; however, this increase slowed at fertilization rates above 33 %. Based on the yield and fertilizer pollution control, fertigation with 33 % of the traditional fertilizer dose should be considered for tea production in the water source area.