Effect of nitrogen fertilizer reduction-high cultivation density-micro fertilizer increment on rice yield and nitrogen use efficiency in saline-sodic soil

Saline-alkaline land is the important strategic reserve land in our country.Aiming at solving the problem of excessive nitrogen application, we planted rice variety Dongdao 4 and studied the effects of nitrogen fertilizer reduction-high density cultivation-micro-fertilizer increment mode on rice yield, yield components and nitrogen use efficiency in an 11-year ameliorating saline-sodic field.The experiment included 6 treatments: no fertilizer; no nitrogen; conventional planting (pure N190 kg·hm^-2 and conventional cultivation density); nitrogen fertilizer reduction-high cultivation density-micro fertilizer increment mode1, pure N170 kg·hm^-2+high cultivation density+micro fertilizers; nitrogen fertilizer reduction-high cultivation density-micro fertilizer increment mode2, pure N160 kg·hm^-2+high cultivation density+micro fertilizers; nitrogen fertilizer reduction-high cultivation density-micro fertilizer increment mode3, pure N150 kg·hm^-2+high cultivation density+micro fertilizers.The results showed that the modes increased the rice yield by 4.8%~8.0%.The nitrogen partial productivity was increased by 19.2%~31.1%, while the nitrogen agronomic utilization rate was increased by 63.6%~133%.A stepwise regression method was used to establish the rice yield prediction model.Considering all the factors, the nitrogen fertilizer reduction-high cultivation density-micro fertilizers increment improved the rice yield and nitrogen use efficiency based on the saline-sodic soil amelioration.The findings provide a foundation for the fertilizer reduction and cost-saving, stable yield and efficiency-increasing of rice in saline-sodic soil.