施氮量对北疆滴灌春小麦-青贮玉米氮素利用率及土壤硝态氮的影响

Effects of Nitrogen Application Rate on NUE and Soil Nitrate Content of Spring Wheat-Silage Maize in Northern Xinjiang

【目的】研究新疆北疆滴灌春小麦-青贮玉米种植模式中土壤硝态氮分布规律。【方法】研究前茬春小麦选用新春6号、后茬青贮玉米选用新饲玉13号作为材料,其中前茬设置4个施氮处理(即纯氮量对照0.0、240.0、360.0、480.0kg/hm^2,用代码Nw0、Nw1、Nw2和Nw3表示),后茬设置4个施氮量处理(即对照0.0、225.0、337.5、450.0kg/hm^2,用代码Nc0、Nc1、Nc2和Nc3表示),并于前茬春小麦3个生育时期,后茬青贮玉米5个生育时期,分别取0~20、20~40和40~60cm三个层次土样,用AA3连续流动分析仪测定土壤硝态氮含量。【结果】土壤硝态氮含量总体随着施氮量的增加而增加,随着生育期的推进先增加后减少,春小麦在开花期达到峰值,青贮玉米在吐丝期达到峰值,且前茬硝态氮残留量的增加对后茬土壤硝态氮含量有提高的作用;前后茬0~20、20~40和40~60cm三个层次土壤硝态氮含量随着土层的加深而减少,随着施氮量的增加而增加,中、高施氮量(前茬360.0和480.0kg/hm^2,后茬337.5和450.0kg/hm^2)会促进土壤硝态氮向下层土移动。产量及产量构成因素上,前后茬均表现为:随着施氮量的增加,产量及构成因素先增加后减少,春小麦在360.0kg/hm^2施氮处理下产量最高,达6713.39t/hm^2,青贮玉米在225.0kg/hm2施氮处理下产量最高,达88.91t/hm^2(鲜重)。随着施氮量的增加,农学利用率和氮肥偏生产力逐渐降低。【结论】在北疆地区春小麦-青贮玉米种植模式下,采用前茬360.0kg/hm^2、后茬225.0kg/hm^2的施氮组合,有利于实现该种植模式的高产和氮素高效利用。

【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/hm^2, and the silage maize was treated with 4 nitrogen treatments, which were 0 (CK), 225, 337.5, 450 kg/hm^2. 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/hm^2 and 480.0 kg/hm^2, silage maize 337.5 kg/hm^2 and 450.0 kg/hm^2) 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/hm^2 was up to 6,713.39 t/hm^2, and that of silage maize was the highest, up to 88.91 t/hm^2 (fresh weight ) under 225 kg/hm^2 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/hm^2 before stubble and 225.0 kg/hm^2 after stubble will be beneficial to the realization of high yield and high efficiency utilization of nitrogen in the planting mode.