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以华北平原菜地为研究对象,通过控制灌溉量设置不同的土壤水分对照,利用稳定同位素~(15)N自然丰度法,结合传统的乙炔抑制试验,对不同土壤水分条件下的N_2O排放、N_2O同位素特征值以及同位素异位体位嗜值(SP值)变化规律进行分析,以阐明不同水分条件下N_2O的排放规律及其来源.结果表明:水分条件显著影响N_2O排放,相比于50%土壤孔隙含水率(WFPS),70%WFPS的水分条件下N_2O的排放较高.N_2O的排放集中在施肥前期,在施肥中后期迅速减弱.50%WFPS条件下,N_2O的排放最初以硝化作用为主,占比约为90%,随后硝化作用迅速下降,反硝化变成主导作用,施肥7 d后即达到80%以上;而70%WFPS条件下初期则以反硝化为主,占比约为70%,随后下降至40%左右,施肥10 d后逐渐升高至80%.整体上,N_2O的排放主要以反硝化作用为主,不同水分处理对土壤硝化、反硝化作用的影响主要体现在施肥前期,后期均以反硝化为主.综上,建议华北地区的菜地生产应适当降低灌溉量,以减少N_2O排放.
Taking the vegetable farmland in the North China Plain as the research object, different soil moisture control was set by controlling the amount of irrigation, the natural isotope abundance (15) N and the traditional acetylene inhibition test were used to control the N2O emission under different soil moisture conditions, N_2O isotopic eigenvalue and SP value of different isotopes to elucidate the law and source of N_2O emission under different water conditions.The results showed that the water conditions significantly affected the N_2O emission compared with 50% The pore water content (WFPS) of 70% WFPS was higher under the condition of moisture, N 2 O emission was concentrated in the early stage of fertilization and rapidly decreased in the middle and late stage of fertilization.Under the condition of 50% WFPS, N 2 O was mainly nitrified , Accounting for about 90%, followed by rapid decline in nitrification, denitrification became the leading role, 7 days after fertilization reached more than 80%; and 70% WFPS initial denitrification, accounting for about 70 %, Then decreased to about 40%, and gradually increased to 80% after 10 days of fertilization. Overall, the main emission of N 2 O was denitrification, and the effects of different water treatments on soil nitrification and denitrification were mainly reflected in fertilization Pre and post are Denitrification based. In summary, the proposed North China’s vegetable production should be appropriate to reduce the amount of irrigation to reduce emissions N_2O.