土壤磷含量与有效性对N_(2)O排放量的影响元分析

Effects of soil phosphorus concentration and availability on N_(2)O emissions:a meta-analysis

土壤氧化亚氮(N_(2)O)主要产生于土壤微生物参与的氮循环过程,其排放量受磷含量及有效性影响。添加磷肥有助于缓解陆地生态系统磷限制,提升土壤有效磷含量,进一步影响土壤微生物对氮的利用,同时控制N_(2)O排放。然而不同独立实验中N_(2)O对外源磷添加的响应差异较大。研究从发表的中、英文文献中收集了54份关于施用磷肥与N_(2)O排放量的观测结果,采用元分析方法确定添加外源磷后N_(2)O排放量的响应差异及潜在影响因素。结果表明:(1)外源磷添加对土壤N_(2)O排放量影响不显著;但在磷肥施用量>50 kg P/hm^(2)的室外实验中土壤N_(2)O排放量显著降低了32.5%;施用NaH_(2)PO_(4)的室内实验中N_(2)O排放量显著降低了18.4%。(2)土壤N_(2)O对外源磷添加响应的高变异性是磷肥施用量和土壤含水量、土壤pH、土地利用类型、磷肥种类、纬度和实验时间多种影响因素共同作用的结果。(3)室外和室内实验回归分析中总磷、有效磷回归系数分别为-1.433(P<0.001)、-0.043(P<0.001),随磷含量增加N_(2)O排放量具有降低趋势。研究结果表明识别土壤磷与N_(2)O的作用关系有助于为理解元素生物地球化学循环和缓解全球气候变暖提供新的认识。

Soil nitrous oxide(N_(2)O)is produced primarily by nitrogen cycling processes involving soil microbes,and its emission is affected by phosphorus concentration and availability.The application of phosphorus fertilizer contributes to alleviating phosphorus limitation in the terrestrial ecosystems.It enhances soil available phosphorus concentration,which further affects nitrogen utilization by soil microbes and controls N_(2)O emissions.However,the response of N_(2)O to exogenous phosphorus addition varied widely in independent experiments.In this study,54 observations on phosphorus fertilizer application and N_(2)O emissions were collected from the published Chinese and English literature,and a meta-analysis was used to determine the differences in response and potential influencing factors of N_(2)O emissions after applying exogenous phosphorus.The results are as follows.(1)The effect of exogenous phosphorus addition on soil N_(2)O emissions was not significant.However,soil N_(2)O emissions were significantly reduced by 32.5%in the outdoor experiments with the application of phosphorus fertilizer>50 kg P/hm^(2).And soil N_(2)O emissions were significantly reduced by 18.4%in the indoor experiments with the application of NaH_(2)PO_(4).(2)The high variability of soil N_(2)O response to exogenous phosphorus addition was the result of the combined effect of various influencing factors such as phosphorus fertilizer application rate and soil moisture,soil pH,land use type,phosphorus fertilizer type,latitude,and experimental time.(3)The regression coefficients of total phosphorus and available phosphorus in the regression analysis of outdoor and indoor experiments were-1.433(P<0.001)and-0.043(P<0.001),respectively,and the N_(2)O emission had a decreasing trend with the increase of phosphorus concentration.These results implied that identifying the relationship between soil phosphorus and N_(2)O could provide new insights for understanding elemental biogeochemical cycles and mitigating global warming.