田间老化生物质炭减缓稻麦轮作系统土壤N2O排放能力降低的机理  

Mechanisms of Diminishing Capacity for Mitigating Nitrous Oxide Emissions by Field-Aged Biochar in the Rice-Wheat Rotation Ecosystem

作　　者：朱爽阁 张前前 徐昕彤 毕瑞玉 宋燕凤 熊正琴 ZHU Shuangge;ZHANG Qianqian;XU Xintong;BI Ruiyu;SONG Yanfeng;XIONG Zhengqin(Jiangsu Key Laboratory of Low Carbon Agriculture and GHGs Mitigation,College of Resources and Environmental Sciences,Nanjing Agricultural University,Nanjing 210095,China)

机构地区：[1]南京农业大学资源与环境科学学院,江苏省低碳农业与温室气体减排重点实验室,南京210095

出　　处：《土壤学报》2023年第3期716-725,共10页Acta Pedologica Sinica

基　　金：国家自然科学基金项目(41977078);江苏省研究生科研与实践创新计划(KYCX21_0618)资助。

摘　　要：生物质炭作为一种重要的土壤调节剂,在固碳减排尤其氧化亚氮(N_(2)O)减排方面的作用日益突出。为明确生物质炭对田间N_(2)O排放的持续效应及其作用机理,通过田间定位试验,分析稻麦轮作体系新鲜和田间不同时间老化生物质炭对N_(2)O排放的影响。试验共设置5个处理,分别为CK(不施氮肥和生物质炭)、N(施氮肥)、NB0y(氮肥+新鲜生物质炭)、NB2y(氮肥+2年老化生物质炭)和NB5y(氮肥+5年老化生物质炭),动态监测稻麦轮作周期N_(2)O排放,测定水稻和小麦收获后土壤理化性质和氮循环功能基因丰度。结果表明,生物质炭显著降低土壤N_(2)O累积排放量32.4%~54.0%,且表现为NB0y>NB2y>NB5y。与N处理相比,NB0y、NB2y和NB5y处理显著提高土壤pH 0.6~1.2个单位、土壤有机碳(SOC)含量21.4%~58.6%、硝态氮( NO_(3)^(-)-N)含量1.7%~31.3%,对土壤pH改善能力随着生物质炭老化而下降。生物质炭处理显著提高nosZ基因丰度54.9%~249.4%,土壤(nirS+nirK)/nosZ比值随着生物质炭老化而增加。相关性分析表明,土壤N_(2)O累积排放量与pH呈显著负相关,与 NO_(3)^(-)-N含量和amoA-AOB(氨氧化细菌)丰度呈显著正相关。因此,新鲜和田间不同时间老化生物质炭均能显著改善土壤理化特性,降低土壤N_(2)O排放且新鲜生物质炭的作用效果优于老化生物质炭。土壤NO_(3)^(-)-N含量及(nirS+nirK)/nosZ比值的增加,是导致老化生物质炭减排N_(2)O能力降低的主要原因。【Objective】Biochar is an important soil amendment material,as it plays an increasingly prominent role in carbon sequestration and greenhouse gas mitigations,especially in nitrous oxide(N_(2)O)mitigation.To investigate the effects and the mechanisms of the biochar aging process on soil N_(2)O emissions under a rice-wheat rotation system,an in situ field experiment was conducted.【Method】Five treatments were established as follows:CK(without urea and biochar),N(urea),NB0y(urea with fresh biochar),NB2y(urea with 2-year aged biochar)and NB5y(urea with 5-year aged biochar).Soil N_(2)O emission dynamics were monitored during rice and wheat annual rotation.Also,soil physicochemical characteristics and the abundance of relevant microbial functional genes during the N_(2)O production process were determined after rice and wheat harvest.【Result】Biochar treatment significantly reduced the cumulative N_(2)O emissions by 32.4%–54.0%,with the reduction capacity following NB0y>NB2y>NB5y.Compared with the N treatment,NB0y,NB2y and NB5y treatment significantly increased soil pH by 0.6–1.2 units,soil 3 NO^(-)_(3)-N content by 1.7%–31.3%,and soil organic carbon(SOC)content by 21.4%–58.6%.Nevertheless,the ability of biochar to improve soil pH was decreased with aging.Also,NB0y,NB2y and NB5y treatments significantly increased the abundance of nosZ gene by 54.9%–249.4%,and the soil(nirS+nirK)/nosZ ratio increased with the biochar age.Meanwhile,the cumulative N_(2)O emissions showed a significant negative correlation with soil pH,and a positive correlation with 3 NO^(-)_(3)content and amoA-AOB gene abundance.【Conclusion】In summary,both fresh and aged biochar can significantly improve soil physical and chemical properties and decrease soil N_(2)O emissions,but the effect of fresh biochar was better than that of aged biochar.The mitigation capacity of aged biochar decreased mainly due to the increase of soil NO_(3)^(-)-N content and(nirS+nirK)/nosZ ratio.

关 键 词：稻麦轮作系统 老化生物质炭 氧化亚氮(N_(2)O)排放 

分 类 号：S158[农业科学—土壤学]