水氮调控对设施土壤氨挥发特征的影响

基于连续6年设施番茄水氮调控定位试验,采用高分辨激光光谱法观测分析灌水下限(土壤水吸力为W_1:25 kPa、W_2:35 kPa、W_3:45 kPa)和施氮量(N_1:75 kg N/hm~2、N_2:300 kg N/hm~2、N_3:525 kg N/hm~2)对设施土壤氨挥发通量、累积挥发量、番茄产量及单产累积排放量的影响。结果表明:灌水下限、施氮量及两者交互作用极显著的影响设施土壤氨挥发通量峰值、累积挥发量、单产氨挥发累积量、氨挥发损失率和番茄产量。氨挥发通量表现为施氮后6～8天氨挥发达到峰值。经验S模型可以较好地表征基肥和追肥2个时期氨挥发累积量随时间的变化,氨挥发特征参数表现为基肥期以灌水下限和水氮交互影响为主,追肥期以施氮量和水氮交互影响为主。与基肥相比,采用滴灌追肥可显著的降低氨挥发累积量94.78%～96.30%。受土壤pH和土壤NH_4~+-N含量及施肥带比例影响,氨挥发的氮损失率在0～2%。施氮量为300 kg N/hm~2和灌水下限25 kPa组合的水氮处理(W_1N_2)是协调氨挥发量和设施番茄产量的最佳水氮管理模式。

Effects of Water and Nitrogen Regulation on Soil Ammonia Volatilization in Greenhouse

Based on a six-year field experiment, the effects of irrigation lower limits (soil water suction of 25, 35 and 45 kPa, marked as W₁, W₂ and W₃ respectively) and nitrogen fertilization rates (75, 300 and 525 kg N/hm², marked as N₁, N₂ and N₃ respectively) on soil ammonia volatilization flux, cumulative volatilization, tomato yield and ammonia per unit yield cumulative emission were studied in greenhouse by the high-resolution laser spectroscopy. The results showed that the peak of ammonia volatilization flux, cumulative volatilization, ammonia volatilization accumulation, ammonia volatilization loss rate and tomato yield were significantly affected by the irrigation lower limits, nitrogen fertilization rates and their interactions. The peak of ammonia volatilization flux occurred after 6~8 days of nitrogen application. The empirical sigmoidal model could be used to well fit the changes of ammonia volatilization accumulation with time in the basal and topdressing periods. The model parameters of ammonia volatilization were mainly affected by the irrigation lower limit and its interaction with nitrogen in the basal period, and which was mainly affected by nitrogen fertilization and its interaction with irrigation in the topdressing period. Drip fertigation could significantly reduce ammonia volatilization by 94.78%~96.30% compared with the basal fertilization. The nitrogen loss rate of ammonia volatilization ranged from 0 to 2% under the influence of soil pH, soil NH₄⁺-N content and nitrogen fertilization zone proportion. Considering the mitigation of ammonia volatilization and increase of tomato yield, it was concluded that the optimal management in greenhouse was W₁N₂ treatment.