橡胶林下砖红壤不同氮肥处理氨挥发特征

摘要

Ammonia volatilization is an important pathway of nitrogen fertilizer loss in gas form, which evidently affects the regional nitrogen cycle and leads to a series of serious environmental problems. At present, there is not much knowledge about ammonia volatilization from acidic red latosol after urea application. In this paper, the characteristics of ammonia volatilization from acidic red latosol after urea application were studied by the field in situ determination of venting method and the corresponding mitigation strategies were proposed,which were hoped to provide a scientific basis for the optimal management of nitrogen in rubber(Hevea brasiliensis) plantation. 6 treatments were designed as follows: no nitrogen; urea deep placement; urea top-dressing followed by irrigation water (simulated precipitation); urea combined with manure; urea added with urease inhibitor N- (n-butyl) thiophosphoric triamide (NBPT); urea top-dressing. The results showed that after urea top-dressing in the acidic red latosol of rubber plantation, soil pH increased dramatically. In 3 days after urea application, the soil pH reached the maximum value of 6.87, then decreased rapidly, and returned to the level of initial status after 7 days. The dynamics of ammonia volatilization was roughly synchronized with the soil pH and ammonium nitrogen concentration changes. The ammonia volatilization process approximately completed within 7 days, and the loss rate was up to 28.19%. Urea added with urease inhibitor NBPT delayed the appearance of ammonia volatilization peak, and the process of ammonia volatilization completed in 12 days with the loss rate of 30.27%. Compared with urea top-dressing, urea added with NBPT did not reduce the ammonia volatilization amount. Of the urea combined with manure, urea deep placement and urea top-dressing followed by irrigation water, the ammonia volatilization process all basically completed within 7 days, and ammonia volatilization loss rates were 13.23%, 5.39% and 1.52%, respectively. Compared with urea top-dressing, these 3 methods could significantly reduce the ammonia volatilization loss rates by 53.05%, 80.87% and 94.61%, respectively. Thus, urea combined with manure, urea deep placement and urea top-dressing followed by irrigation water are the effective measures for the ammonia volatilization reduction in acidic red latosol of rubber plantation after urea application.%氨挥发是氮肥气态损失的重要途径,显著地影响了区域氮循环,导致了一系列严重的环境问题.目前对橡胶(Hevea brasiliensis)林下酸性砖红壤施用尿素后的氨挥发损失了解还不多.采用通气法田间原位研究了酸性砖红壤施用尿素后的氨挥发特征及相应调控措施,为橡胶树氮肥优化管理提供一定的科学依据.试验共设6个处理,分别为:不施氮;尿素深施;尿素表施后灌水(模拟降雨);尿素配施有机肥;尿素添加脲酶抑制剂(N-丁基硫代磷酰三胺,NBPT);尿素表施.结果表明,尿素表施后,表层土壤pH迅速升高.施肥3 d后土壤pH达到最大值6.87,之后迅速下降,7 d后恢复至试验前水平.其氨挥发动态变化与表层土壤pH和铵态氮浓度变化大致同步,整个氨挥发损失过程基本在7 d内完成,损失率高达28.19%;尿素添加脲酶抑制剂NBPT延迟了氨挥发峰值的出现,氨挥发损失过程在12 d内完成,损失率为30.27%.与尿素表施相比,尿素添加NBPT并没有降低氨挥发损失;尿素配施有机肥、尿素深施和尿素表施后灌水的氨挥发损失也基本在7 d内完成,氨挥发损失率分别为13.23%、5.39%和1.52%.与尿素表施相比,这3种方法分别显著降低了53.05%、80.87%和94.61%的氨挥发损失.由此可见,尿素配施有机肥、尿素深施和尿素表施后灌水是橡胶林下酸性砖红壤施用尿素的氨挥发减排的有效措施.