气候变暖对西藏青稞农田氨挥发和产量的影响

【目的】研究气候变暖对西藏青稞农田氨挥发特性和青稞产量的影响，为探索减少青稞生产中的氨挥发、提高氮肥利用率提供依据。【方法】在西藏青稞主产区之一的拉萨河谷农区，采用开顶式气室(open-top chamber, OTC)增温系统模拟气候变暖进行大田试验。试验共设置不增温(对照，T0)、增温2℃(T2)和增温4℃(T4)3个处理。将290.25 kg/hm²尿素(纯N 133.5 kg/hm²)分别于播种前(4月12日)基施60%、拔节期(6月6日)和抽穗期(6月20日)各追施20%。测定不同处理青稞农田的土壤氨挥发通量以及青稞生长指标、产量及其构成要素，计算基肥和追肥的氨挥发积累量和氨挥发损失率，分析增温与土壤氨挥发特性以及青稞株高、产量及其构成要素的相关性。【结果】氮肥基施后，T0、T2和T4 3个处理的青稞农田土壤氨挥发通量至播种后第14天达到峰值，且土壤氨挥发通量峰值由大到小表现为T4>T0>T2;T2和T4处理基肥氨挥发周期均为26 d,较T0处理延长了3 d。于抽穗期追施氮肥后，T0、T2和T4 3个处理的土壤氨挥发通量...

Influence of climate warming on ammonia volatilization and yield of Tibetan highland barley farmland

【Objective】This study investigated the influence of climate warming on ammonia volatilization characteristics and highland barley yield in Tibetan farmland to provide basis for the future exploration of reducing ammonia volatilization and improving nitrogen fertilizer utilization in highland barley production.【Method】The open-top chamber (OTC) warming system was used to simulate climate warming in the Lhasa River Valley agricultural area,one of the main producing areas of Tibetan highland barley.Three treatments included no warming (CK,T0),simulated temperature increase of 2 ℃ (T2) and temperature increase of 4 ℃ (T4).Urea application rate was 290.25 kg/hm² (pure N 133.5 kg/hm²),with 60% applied as base fertilizer before sowing (April 12) and 20% applied at jointing (June 6) and heading (June 20),respectively.The ammonia volatilization flux and growth index,yield and components of highland barley were measured.The ammonia volatilization accumulation and ammonia volatilization loss rate of base fertilizer and top fertilizer were calculated.Finally,the correlations between temperature increases and soil ammonia volatilization characteristics,as well as plant height,yield and its factors of highland barley were analyzed.【Result】After nitrogen base application,the soil ammonia volatile fluxes of T0,T2 and T4 treatments reached the peak on the 14th day after seeding,and the peak values were in the order of T4>T0>T2.The ammonia volatilization period of base fertilizer in T2 and T4 treatments was 26 d,which was 3 d longer than that in T0 treatment.After nitrogen fertilizer applied at heading stage,soil ammonia volatile fluxes of T0,T2 and T4 treatments reached the peak immediately,with values in order of T2>T0>T4.The volatilization period of top fertilizer ammonia was shortened by 6 d and 8 d when temperature was increased by 2 ℃ and 4℃,respectively.In the whole growth period of highland barley,soil ammonia volatilization accumulation and ammonia volatilization loss rate in T4 with 4 ℃ temperature increase were increased significantly by 33.83% and 33.91% compared with T0 treatment,while T2 treatment had no significant changes.Base fertilizer ammonia volatilization was the main source of volatilization in Tibetan highland barley soil.With the growth and development of highland barley,the biomass and plant height in T0,T2 and T4 showed an increasing trend,the plant water content showed a decreasing trend,while the number of tillers decreased after initial increase.The effective panicle numbers of T2 and T4 treatments had no significant difference from that of T0 treatment.Compared with T0 treatment,the number of grains per spike,thousand grains mass and yield of T4 treatment were significantly reduced,while those of T2 treatment had no significant changes.The correlation analysis showed that the simulated temperature increase was positively correlated with biomass and plant height of highland barley,while negatively correlated with weight of 1 000 grains,number of grains per spike and yield.【Conclusion】There were no significant changes in soil ammonia volatilized flux and highland barley yield in the whole barley growth period with 2 ℃ temperature increase.The ammonia volatilization flux in the whole growth period of highland barley increased significantly,while the yield of highland barley decreased significantly with 4 ℃ temperature increase.In future,the utilization rate of nitrogen fertilizer should be increased by reducing ammonia volatilization of base fertilizer and regulating water content of highland barley and plant height,so as to ensure stable and high yield.