Effects of combined application of chemical fertilizer and organic manure on wheat yield and leaching of residual nitrate-N in dryland soil

Abstract

The effects of optimum nitrogen (N) fertilization rate with and without adding manure on wheat yield and leaching of residual nitrate-N in soil profile were examined in Weibei dryland, Shaanxi with a field experiment combined different N fertilization rates (0, 75, 150, 225, 300 kg N·hm-2) and organic manure (0 and 30 t·hm-2). The results showed that, compared to chemical N fertilizer, combined application of inorganic fertilizer and organic manure increased winter wheat yield by 14.7% when N fertilization rate was reduced by 27.1%. The highest yield was obtained when 150 kg·hm-2 of N rate was combined with the manure (N150+M). The combination of N fertilizer and manure promoted N uptake of wheat grain and increased N use efficiency by 20.2%. The highest N use efficiency was recorded in the N150+M treatment. In addition, the lea-ching of residual nitrate-N during the wheat growing season and the leaching of nitrate-N during summer fallow were decreased. When N application rate was lower than 115 kg·hm-2, N fertilizer combined with organic manure reduced the amount of nitrate-N leaching in summer fallow. We recommend the combined application of organic manure with about 150 kg·hm-2 of N fertilizers in Weibei dryland to guarantee high winter wheat yield, N use efficiency, and reduce excessive residue of fertilizer N in the soil.