长期定位施用牛粪对夏玉米-冬小麦体系农田N_2O和NO排放的影响

Effect of Long-term Dairy Manure Amendment on N_2O and NO Emissions from Summer Maize-Winter Wheat Cropping Systems

利用静态暗箱法对关中平原27 a长期定位施肥农田氧化亚氮(N_2O)和一氧化氮(NO)排放通量进行周年(2017年6月到2018年6月)观测,目的是阐明N_2O和NO的排放特征及其影响因子,定量评估施用牛粪对气体排放的影响.田间试验采用随机区组试验设计,设置3种处理.对照(CK)处理全年不施肥.全化肥(NPK)和化肥加牛粪(NPKM)处理全年施氮(N)量为353 kg·hm^(-2),其中夏玉米季为188 kg·hm^(-2),均为尿素N;冬小麦季为165 kg·hm^(-2),NPK处理全部为尿素N,而NPKM处理尿素N与牛粪N的比例为3∶7.结果表明,CK处理气体排放通量较低且无明显季节变化,NPK和NPKM处理气体排放高峰主要与施肥和灌溉有关,N_2O和NO排放最高峰值分别为103. 0 g·( hm^2·d)^(-1)和71. 0 g·( hm^2·d)^(-1),均出现在NPKM处理玉米季.当土壤温度高于20℃时,NPK和NPKM中NO/N_2O比均与土壤充水孔隙度呈显著负相关关系(P <0. 01),说明土壤温度和水分含量共同影响气体排放.各处理N_2O年排放量分别为0. 21、2. 32和2. 15 kg·hm^(-2),NPK与NPKM处理间差异不显著(P=0. 74); NO年排放量分别为0. 23、0. 80和1. 46 kg·hm^(-2),NPK和NPKM处理间差异显著(P <0. 05).说明长期施用牛粪对N_2O排放无影响,但可显著增加NO排放.

Annual nitrous oxide( N2O) and nitric oxide( NO) emissions were measured within a 27 year fertilization experiment in Guanzhong Plain. Gas samples were collected using static chambers from June 2017 to June 2018. The primary objectives of this study were to quantify the variations in N2O and NO emissions and evaluate the effect of manure amendment on gas losses. Three treatments were set up in the field using a completely random block design. The control treatment( CK) remained unfertilized throughout the year. The synthetic fertilizers( NPK) and NPK plus dairy manure( NPKM) treatments received an annual nitrogen( N) input at a rate of 353 kg·hm-2. In the summer maize season,the NPK and NPKM treatments received urea as a N source at 188 kg·hm-2. In the winter wheat season,the NPK treatments received urea at 165 kg·hm-2. The NPKM treatment received the same amount of N as the NPK treatment but with 30% from urea and 70% from dairy manure. The results showed that N2O and NO emissions from the CK treatment were consistently low during the experimental period. Large emission peaks were captured in the NPK and NPKM treatments,mostly responding to fertilizer application and irrigation. The largest N2O and NO peaks were up to 103. 0 g·( hm2·d)-1 and 71. 0 g·( hm2·d)-1,respectively,and both occurred in the NPKM treatment during the summer maize season. The NO/N2O ratio was negatively related to soil water-filled pore space( P < 0. 01) at soil temperatures above 20℃ for the NPK and NPKM treatments,indicating the regulatory effect of soil temperature and water content on gas fluxes. Annual N2O emissions from the CK,NPK,and NPKM treatments were 0. 21 kg·hm-2,2. 32 kg·hm-2,and 2. 15 kg·hm-2,respectively,with a non-significant difference between the NPK and NPKM treatments( P = 0. 74). Annual NO emissions from the CK,NPK,and NPKM treatments were 0. 23 kg·hm-2,0. 80 kg·hm-2,and 1. 46 kg·hm-2,respectively,with a significant difference between the NPK and NPKM treatments( P < 0. 05).We concluded that long-term dairy manure amendment did not influence N2O emissions but increased NO emissions.