华北平原氮肥周年深施对冬小麦-夏玉米轮作体系土壤氨挥发的影响

The effects of deep application of nitrogen fertilization on ammonia volatilization in a winter wheat/summer maize rotation system in the North China Plain

氮肥深施能有效减少土壤氨挥发,然而目前国内外关于小麦-玉米轮作体系氮肥深施缺乏周年系统性研究。本试验于2018年10月—2019年10月在中国科学院栾城农业生态系统试验站小麦-玉米轮作农田进行,利用动态箱法研究不同深施模式氨挥发损失率、氨挥发特征,旨在探讨冬小麦-夏玉米轮作体系下土壤氨排放对氮肥深施的响应,为减少农业源氨排放和优化农田施肥提供理论依据。试验设置5个处理:不施肥(CK)、常规肥料表施(T1)、缓释肥表施(T2)、缓释肥基追肥分层深施(T3)、缓释肥一次性分层深施(T4)。结果表明:氨挥发主要发生在玉米追肥季,占全年氨挥发量的84.84%;T1、T2、T3和T4处理的周年氨挥发累积量分别为22.75 kg·hm−2、6.17 kg·hm−2、2.25 kg·hm−2和0.55 kg·hm−2,分别占总施肥量的4.86%、1.32%、0.48%和0.13%。与常规肥料表施(T1)相比,缓释肥处理(T2、T3和T4)分别降低72.88%、90.11%和97.32%的氨挥发损失;一次性深施处理(T4)能避开土壤氨高挥发期,周年氨挥发累积量与不施肥处理(0.43 kg·hm−2)没有显著差异,且显著低于表施处理。CK、T1、T2、T3和T4全年产量分别为8.31 t·hm−2、13.20 t·hm−2、12.66 t·hm−2、14.42 t·hm−2和14.22 t·hm−2;与常规肥料表施(T1)相比,缓释肥深施(T3和T4)均可提高作物产量,分别增产9.25%和7.75%。而缓释肥表施(T2)产量略有降低。综合考虑土壤氨排放和作物产量,缓释肥表施(T2)可以显著降低土壤氨挥发,但是作物产量不稳定;而氮肥深施(T3、T4)能在保证作物高产的基础上显著降低土壤氨排放,是一种高效、简便、环境友好的施肥方式。

The deep application of nitrogen fertilizers can reduce soil ammonia volatilization,but no annual systematic study in a winter wheat/summer maize rotation system exists.Nitrogen fertilizer was deeply applied to soil from a winter wheat/summer maize rotation system to determine the effects on ammonia emissions and optimize farmland fertilization.Five treatments were used from October 2018 to October 2019:no fertilization(CK),conventional fertilizer surface-application(T1),slow-release fertilizer surface-application(T2),twice layered deep-application of slow-release fertilizer(T3),and single layered deep-application of slow-release fertilizer(T4).Ammonia volatilization primarily occurred in the corn top-dressing season and accounted for 84.84%of the annual ammonia volatilization.The cumulative amounts of annual ammonia volatiles were 22.75(T1),6.17(T2),2.25(T3),and 0.55 kg·hm−2(T4),accounting for 4.86%,1.32%,0.48%,and 0.16%of the total fertilizer application,respectively.The slow-release fertilizer treatments reduced the ammonia volatilization loss by 72.88%(T2),90.11%(T3),and 96.30%(T4)compared to T1.The single deep application treatment(T4)avoided the summertime high soil ammonia volatilization period,and the cumulative annual ammonia emissions were comparable to the unfertilized emissions(0.43 kg·hm−2).The annual yields were 8.31(CK),13.20(T1),12.66(T2),14.42(T3),14.22(T4)t·hm−2;and compared with T1,the slow-release fertilizer deep application increased the crop yield by 9.25%(T3)and 7.75%(T4).The surface application of slow-release fertilizer(T2)slightly decreased the yield but significantly reduced the ammonia volatilization amount.In conclusion,the deep application of slow-release nitrogen fertilizer improved crop yield and reduced soil ammonia emissions,and was shown to be a simple,efficient,and environment-friendly fertilization method.