Effect of N application on nitrogen absorption and utilization of spring maize under different soil fertilities

Field experiments were conducted to study the effect of different nitrogen application rates on maize yield,nitrogen uptake and utilization under different soil fertilities in Jilin province.The results showed that,the highest N application rates under maximum yields were N 251 and 206 kg/ha for Fanjiatun and Yushu respectively,and the economic optimum N application rates under economic optimum yields were N 227 and 134 kg/ha for Fanjiatun and Yushu respectively.The maximum N absorption rate and total N uptake were significantly improved with the increasing N application rates,and the date of the maximum N absorption rate occurred earlier in Fanjiatun site.The residual nitrate nitrogen in 0-30 cm soil profile increased with N application rates,and nitrate accumulation in 0-30 cm soil profile was observed higher in Yushu than that in Fanjiatun.The nitrogen agronomic efficiency,nitrogen recovery efficiency and nitrogen partial factor productivity in Fanjiatun with lower soil fertility were higher than those in Yushu with higher soil fertility.In summary,it was suggested that for the site like Fanjiatun with lower soil fertility,the high yield could be reached by increasing N application rate,while for the site like Yushu with higher soil fertility,N application rate should be controlled in order to increase the yield and improve N use efficiency.