Effects of combined application of common urea and slow-release urea on dry matter accumulation and nitrogen utilization of summer maize

Aiming at the problems of unreasonable application of nitrogen fertilizer and low fertilizer utilization in maize in low plain of Hebei Province, ’Xianyu 688’(XY688) and ’Jifeng 2’(JF2) were used as experimental materials to study the effects of different ratios of common urea and slow-release urea on dry matter accumulation and nitrogen utilization of summer maize in Xinji Experimental Station. The results showed that:(1) ’XY688’ had higher grain yield and nitrogen use efficiency than those of ’JF2’.(2) The grain yield, nitrogen uptake by mature plants, nitrogen use efficiency and nitrogen harvest index of ’XY688 and ’JF2’ were the highest when common urea and slow-release urea were mixed at a ratio of 3: 7. The reason for obtaining higher yield under this treatment was that there were more ears and grains per ear, and the reason for obtaining higher nitrogen uptake by plants was that they had higher nitrogen uptake after anthesis and nitrogen uptake by vegetative organs before anthesis.(3) Under the mixed treatment of common urea and slow-release urea at 3∶7, varieties ’XY688’ and ’JF2’ had higher leaf area and photosynthetic rate after anthesis, which improved the strong photosynthetic products for the post-anthesis growth of maize. The results can provide a scientific basis for the popularization and application of slow-release urea in summer maize production in Hebei plain.