Abstract: 【Objective】 To find out the distribution of soil nitrate nitrogen in the spring wheat-silage maize planting mode of drip irrigation in northern Xinjiang. 【Method】 In this study, Xinchun No.6 and Xinyu No.13 were selected as experimental materials. Four kinds of nitrogen treatments were applied to spring wheat, which were pure nitrogen content 0 (CK), 240, 360, 480 kg/hm², and the silage maize was treated with 4 nitrogen treatments, which were 0 (CK), 225, 337.5, 450 kg/hm². In the three growth stages of spring wheat, three different growth stages of silage-maize were taken from 0-20 cm, 20-40 cm and 40-60 cm, and the soil nitrate nitrogen content was determined by AA3 continuous measuring instrument. 【Result】 The changes of nitrate nitrogen content in the soil of spring wheat and silage maize with time were as follows: the content of soil nitrate nitrogen increased with the increase of nitrogen application rate, and increased first and then decreased with the advance of growth period. Spring wheat reached its peak during flowering stage, and silage maize peaked at spinning stage. The increase of nitrate nitrogen residue in the previous crop could increase the nitrate nitrogen content in the later soil. The spatial variation rule of soil nitrate nitrogen content was as follows: the content of nitrate nitrogen in soil of 0-20 cm, 20-40 cm and 40-60 cm soil before and after stubble decreased with the deepening of soil layer, and increased with the increase of nitrogen application rate. Medium and high nitrogen application (wheat 360.0 kg/hm² and 480.0 kg/hm², silage maize 337.5 kg/hm² and 450.0 kg/hm²) promoted the movement of nitrate nitrogen to the lower layer.In terms of yield and composition factors, both before and after the performance were as follows: with the increase of nitrogen application rate, the yield and composition factors increased first and then decreased. The yield of spring wheat under the nitrogen treatment of 360 kg/hm² was up to 6,713.39 t/hm², and that of silage maize was the highest, up to 88.91 t/hm² (fresh weight ) under 225 kg/hm² nitrogen treatment. In terms of NUE, the annual NUE showed that the NP and NAE gradually decreased with the increase of nitrogen application rate. 【Conclusion】 Considering the combined nitrogen application rate, soil nitrate nitrogen content, yield and NUE, under the spring wheat-silage maize planting mode in northern Xinjiang, the nitrogen application combination of 360.0 kg/hm² before stubble and 225.0 kg/hm² after stubble will be beneficial to the realization of high yield and high efficiency utilization of nitrogen in the planting mode.
Key words: nitrogen application rate; spring wheat-silage maize; nitrate nitrogen content; yield; NUE
Fund project:Supported by the National Natural Science Foundation of China (31460334); Key Projects in the National Science & Technology Pillar Program during the Twelfth Five-year Plan Period (2012BAD42B03)