Effect of nitrogen application rates on the concentration and distribution of nutrients in maize

A consecutive 5 years field trial in the lower reach plain of Liaohe River was conducted to study the effect of different nitrogen application rates on the yield,concentration of NPK,distribution of NPK in maize,and the harvested NPK from producing each unit of grains.The results showed that with the raise of N fertilizer rate,the concentration of P and K was decreasing.The results also indicated that there was significant correlation between the yield and the ratio of N and K content in grain and stalk.The better the crop growth,the less consumption of nutrients in producing each unit of grain products,implying that better condition of crop growth was beneficial to increase the utilization efficiency of nutrients.