施肥方式对黄土高原旱作春玉米农田土壤氨挥发的影响

【目的】通过两年田间氨挥发测定,研究不同施氮量和不同施氮方式对黄土高原旱作春玉米农田土壤氨挥发的影响。【方法】 该试验采用裂区试验设计,主处理设置0、180、300 kg·hm^-2 3个氮肥用量,同一施氮量下副区分尿素一次性基施（UR）、尿素分次施用（URT）（基肥40%,十叶期追肥60%）以及尿素与控释尿素掺混一次性基施（CRU）3种施氮方式,采用海绵吸收通气法进行原位测定。【结果】 （1）对于施基肥后的氨挥发速率,3种施肥方式均出现挥发峰值,且UR处理的氨挥发峰值高于另外两种施肥方式,特别是在高施氮量的情况下;对于追肥后的氨挥发,只有URT处理出现峰值,且高于基肥后的挥发峰值。（2）氨挥发累积量随着施氮量的增加而增加。在同等施氮量处理下,URT处理氨挥发累积量最高（2.88—36.84 kg·hm^-2）,且主要集中在追肥期（占整个生育期的72.2%—90.4%）;其次是UR处理（1.08—10.07 kg·hm^-2）;CRU处理氨挥发累积量最低（0.96—5.69 kg·hm^-2）。（3）施氮量和施肥方式对氨挥发量的交互作用极显著,氨挥发的年间差异主要是受到施肥后的降雨影响。【结论】 对于西北旱作覆膜春玉米,尿素与控释尿素掺混一次性施用方式（CRU）既能减少追肥人工投入,又能减低氨挥发损失,可作为该区域值得推广的绿色施肥方式。

Effects of Fertilization Methods on Ammonia Volatilization of Spring Maize in Dry Farming on the Loess Plateau

【Objective】 A two-year on-farm experiment was conducted to evaluate the effects of different fertilization application methods and nitrogen application rates on soil ammonia volatilization of spring maize in dry farming on the Loess Plateau. 【Method】The split zone test design was adopted in the experiment, the main factor included three nitrogen application rates of 0, 180 and 300 kg·hm^-2 (namely N0, N180 and N300, respectively), and the sub-factors included three fertilization methods of solid granular urea one-time basal fertilization (UR), solid granular urea basal and top-dress fertilization (URT, 40% as basal fertilizer and 60% as top-dressing at 10 leaf stage), and common urea and controlled-release urea mixed in one-time basal application (CRU). Sponge absorption ventilation method was used for in-situ determination. 【Result】 (1) As for the ammonia volatilization after basal fertilizer, the three fertilization methods all showed the peak value of ammonia volatilization, and the peak value of ammonia volatilization under UR treatment was higher than that of the other two fertilization methods, especially under the condition of high nitrogen application rate. For the ammonia volatilization after topdressing, only the URT treatment showed the peak value, which was higher than that after basal fertilizer. (2) The accumulation of ammonia volatilization increased with the increase of nitrogen application rate. Under the same nitrogen application rate, the accumulation of ammonia volatilization under URT treatment was the highest (2.88-36.84 kg·hm^-2), which was mainly concentrated in the top dressing period (72.24%-90.4% of the whole growth period). The second was UR treatment (1.08-10.07 kg·hm^-2), while the cumulative ammonia volatilization under CRU treatment was the lowest (0.96-5.69 kg·hm^-2). 3. The interaction between nitrogen application rate and fertilization method on ammonia volatilization was very significant. The annual difference of ammonia volatilization emission was mainly influenced by rainfall after fertilization. 【Conclusion】For spring maize covered with film in dry farming in northwest China, CRU could reduce both the artificial input of topdressing and the loss of ammonia volatilization, which could be used as a green fertilization method worthy of promotion in this area.