2012年5月2014年6月,采用田间小区试验方法,研究了不同氮肥管理对N_2O与CH_4的排放、土壤硝态氮含量以及苜蓿干草产量的影响.试验共设5个处理:对照(CK)、单施尿素处理(100 kg N·hm~(-2),CF)、尿素(100 kg N·hm~(-2))与腐熟牛粪(60 kg N·hm~(-2))混施处理(DM1)、尿素(100 kg N·hm~(-2))与沼液(60 kg N·hm~(-2))混施处理(DT)及减量尿素(40 kg N·hm~(-2))与牛粪(60 kg N·hm~(-2))混施处理(DM2).结果表明:与CK相比,CF、DM1、DT和DM2处理苜蓿干草产量分别增加44.2%、38.9%、56.3%和30.6%,N_2O排放分别比对照增加52.2%、89.1%、133.7%和59.4%,但各施肥处理对甲烷吸收表现出不同程度的抑制作用.苜蓿生产中,尿素和牛粪处理N_2O-N排放与肥料氮素投入量比值(排放系数)为0.25%~0.28%,而沼液处理N_2O-N排放系数为0.64%,显著高于前者.苜蓿生产中,施用化肥或有机无机混施均能显著增加苜蓿干物质产量,土壤硝态氮深层淋洗风险较小,但增加了CO_(2-equivalent)净排放量.
英文摘要:
Field plot experiment was carried out during May 2012 to June 2014 to investigate the impacts of nitrogen fertilizations on the emissions of nitrous oxide (N_2O) and methane (CH_4) from alfalfa field as well as the dry matter yield and soil nitrate contents. Five treatments including CK, urea (100 kg N·hm~(-2),CF), urea (100 kg N·hm~(-2)) + dairy cattle manure (60 kg N·hm~(-2))(DM1), urea (100 kg N·hm~(-2)) + digestate (60 kg N·hm~(-2)) (DT) and reduced urea (40 kg N·hm~(-2)) + dairy cattle manure (60 kg N·hm~(-2)) (DM2) were conducted. Results indicated that in comparison with CK,CF,DM1,DT and DM2 treatments significantly increased the dry matter yields of alfalfa by 44.2%,38.9%,56.3% and 30.6%,and increased the N_2O emissions by 52.2%,89.1%,133.7% and 59.4%,respectively,whereas the oxidation of atmospheric CH_4 was reduced to different extents by these N management practices. The losses of N_2O-N originated from urea and dairy cattle manure N accounted for 0.25%-0.28% of their inputs,whereas a greater value of 0.64% was observed for digestate N. Applying urea or organic N to alfalfa field could significantly increase the dry matter yield without significant NO_3~--N leaching,however,it would lead to higher net CO_(2-equivalent) emissions of producing 1 t dry matter of alfalfa.