生物质炭添加对土壤氧化亚氮排放影响的研究进展

Research advances in effects of biochar addition on soil nitrous oxide emissions

氧化亚氮(N_(2)O)是一种会破坏平流层臭氧的长寿命温室气体,农业土壤是大气N_(2)O人为排放源中的最大贡献者,因此减少农业土壤N_(2)O排放十分迫切.生物质炭是生物质在低温限氧条件下热解产生的碳材料,具有丰富的孔隙结构.已有研究表明,生物质炭是减少土壤N_(2)O排放的重要手段之一,但对其影响效应和机理的系统报道很少.本文论述了生物质炭对土壤中N_(2)O排放的影响,重点从生物与非生物的角度讨论了生物质炭影响土壤N_(2)O排放可能的机制.从生物角度来看,生物质炭的“石灰效应”会升高土壤pH、改变土壤中微生物过程从而促进N_(2)O还原为N_(2),同时生物质炭也会作为“电子穿梭体”加快这一过程.另外,生物质炭还会增加含有nosZ基因的反硝化细菌数量,促进N_(2)O的还原.而当土壤中N_(2)O主要来自于硝化作用时,生物质炭增加土壤中氨氧化细菌amoA丰度,进而增加土壤N_(2)O排放量.从非生物角度来看,生物质炭能吸附N_(2)O降低土壤N_(2)O释放量,随后其表面的C=C可能会与N_(2)O发生加成反应进而消耗N_(2)O.最后,本文归纳了生物质炭对土壤N_(2)O的影响主要取决于生物质炭特性(原料、热解条件、C/N、施用量、老化程度)、氮肥施用量与土壤理化性质等,同时总结了当前利用生物质炭减少土壤N_(2)O排放研究的不足之处,并对利用其减排土壤N_(2)O的发展方向进行了展望.

Nitrous oxide(N_(2)O)is a long-lived greenhouse gas that can destroy stratospheric ozone.Agricultural soil is the largest contributor to anthropogenic N_(2)O emissions.It is thus urgent to reduce N_(2)O emissions from agricultural soil.Biochar is a carbon material produced by pyrolysis of biomass at low temperature and limited oxygen with rich pore structures.Biochar is one of the important means to reduce greenhouse N_(2)O emissions,but there are few systematic reports on its effect and mechanism.We describe the effects of biochar on N_(2)O emissions from soil.We then discuss the possible mechanisms of biochar on soil N_(2)O emissions.From a biological point of view,the“liming effect”of biochar could increase soil pH and change soil microbial processes to promote the reduction of N_(2)O to N_(2),and also act as an“electron shuttle”in this process.In addition,biochar could increase the population of denitrification bacteria containing nosZ gene to promote the reduction of N_(2)O to N_(2).When soil N_(2)O was mainly generated through nitrification,the addition of biochar could increase the abundance of ammonia-oxidizing bacteria harboring amoA gene in soil,which led to the increase of soil N_(2)O emissions.From an abiotic point of view,the adsorption of N_(2)O on the surface of biochar could reduce the release of N_(2)O emission from soil,and then the surface C=C may react with N_(2)O to consume it.The effects of biochar amendments on N_(2)O emissions depend on the characteristics of biochar(raw materials,pyrolysis conditions,C/N ratio,application rate,and aging degree),nitrogen application rate,and soil physico-chemical properties.Finally,we summarize and put forward further prospect on biochar in reducing N_(2)O emissions from soil.This review will provide an important technical reference for mitigation of N_(2)O emissions from agricultural soil as well as agricultural carbon neutrality in the future.