稻田微氧层和还原层土壤有机碳矿化对氮素添加的响应  

Response of Organic Carbon Mineralization to Nitrogen Addition in Micro-aerobic and Anaerobic Layers of Paddy Soil

作　　者：毛婉琼 夏银行 马冲 朱光旭 王忠诚 涂强 陈香碧[1] 吴金水[1] 苏以荣[1] MAO Wan-qiong;XIA Yin-hang;MA Chong;ZHU Guang-xu;WANG Zhong-cheng;TU Qiang;CHEN Xiang-bi;WU Jin-shui;SU Yi-rong(Key Laboratory of Agro-ecological Processes in Subtropical Region,Institute of Subtropical Agriculture,Chinese Academy of Sciences,Changsha 410125,China;University of Chinese Academy of Sciences,Bejing100049,China;College of Resource and Environment,Hunan Agricultural University,Changsha 41028,China;College of Biology and Environment Engineering,Guiyang University,Guiyang 550005,China;College of Forestry,Central South University of Forestry&Technology,Changsha 410004,China;Helmholtz International Laboratory for Anti-Infectives,Shandong University-Helmholtz Institute of Biotechnology,State Key Laboratory of Microbial Technology,Shandong University,Qingdao 266237,China)

机构地区：[1]中国科学院亚热带农业生态研究所亚热带农业生态过程重点实验室,长沙410125 [2]中国科学院大学,北京100049 [3]湖南农业大学资源环境学院,长沙410128 [4]贵阳学院生物与环境工程学院,贵阳550005 [5]中南林业科技大学林学院,长沙少410004 [6]赫姆霍兹抗感染国际实验室,山东大学赫姆霍兹生物技术研究所,微生物技术国家重点实验室,青岛266237

出　　处：《环境科学》2023年第11期6248-6256,共9页Environmental Science

基　　金：国家重点研发计划项目(2021YFD1901203);国家自然科学基金项目(42177295,41977100);山东大学微生物实验室开放基金项目(M2022-05)。

摘　　要：田间条件下,淹水稻田由于上覆水中溶解氧的扩散作用,使其表层土壤存在约1 cm厚的微氧层,这个特殊层次中碳氮转化的特征尚未明晰.以亚热带典型稻田土壤为对象,采用100 d室内模拟培养试验,结合^(13)C稳定同位素示踪和磷脂脂肪酸(PLFA)分析技术,研究稻田土壤微氧层(0~1 cm)和还原层(1~5 cm)外源新鲜有机碳(^(13)C-水稻秸秆)和原有土壤有机碳矿化对氮肥施用[(NH4)2SO_(4)]的响应规律及其微生物过程.结果表明,氮素添加使土壤总CO_(2)和^(13)C-CO_(2)累积排放量分别提高11.4%和12.3%;培养结束时,氮素添加下还原层比微氧层土壤总有机碳含量和^(13)C回收率分别降低2.4%和9.2%.培养前期(5 d),氮素添加提高还原层微生物总PLFAs,且细菌和真菌PLFAs响应一致,但对微氧层微生物丰度无显著影响;氮素添加对微氧层和还原层总^(13)C-PLFAs丰度均无显著影响,但^(13)C标记细菌和真菌丰度显著降低.培养后期(100 d),氮素添加对微生物总PLFAs的影响与前期一致;氮素添加显著增加还原层^(13)C标记总量及细菌和真菌PLFAs含量,但对微氧层总^(13)C-PLFAs丰度无显著影响.培养期间,还原层土壤铵态氮含量高于微氧层.因此,施加氮素提高了稻田还原层土壤微生物活性,可能是由于还原层土壤具有更高的铵态氮,而大部分微生物偏好利用铵态氮,使还原层微生物生长和活性强于微氧层,进而加速还原层有机碳的微生物利用和分解;与之对应,微氧层土壤由于氨氧化作用,速效氮更多以硝态氮形态存在,因偏好利用硝态氮的微生物缺乏,限制了微氧层有机碳的微生物代谢.综上,氮肥施用增强稻田土壤有机碳矿化损失,但以微氧层响应弱于还原层,提示微氧层对土壤有机碳有一定保护作用.本研究强调了稻田土体的非均一性,其微氧层碳氮转化的特殊性不可忽视,研究结果对优化稻田种植系统氮肥施用形态和方法有一定启示In field conditions,a micro-aerobic layer with 1 cm thickness exists on the surface layer of paddy soil owing to the diffusion of dissolved oxygen via flooding water.However,the particularity of carbon and nitrogen transformation in this specific soil layer is not clear.A typical subtropical paddy soil was collected and incubated with^(13)C-labelled rice straw for 100 days.The responses of exogenous fresh organic carbon(^(13)C-rice straw)and original soil organic carbon mineralization to nitrogen fertilizer addition[(NH_4)_2SO_4]in the micro-aerobic layer(0-1 cm)and anaerobic layer(1-5 cm)of paddy soil and their microbial processes were analyzed based on the analysis of^(13)C incorporation into phospholipid fatty acid(^(13)C-PLFAs).Nitrogen addition promoted the total CO_2 and^(13)C-CO_2 emission from paddy soil by 11.4%and 12.3%,respectively.At the end of incubation,with the addition of nitrogen,the total soil organic carbon(SOC)and^(13)C-recovery rate from rice straw in the anaerobic layer were 2.4%and 9.2%lower than those in the corresponding micro-aerobic layer,respectively.At the early stage(5 days),nitrogen addition increased the total microbial PLFAs in the anaerobic layer with a consistent response of bacterial and fungal PLFAs.However,there was no significant effect from nitrogen on microbial abundance in the micro-aerobic layer.Nitrogen addition had no significant impact on the abundance of total^(13)C-PLFAs in the micro-aerobic and anaerobic layers,but the abundance of^(13)C-PLFAs for bacteria and fungi in the micro-aerobic layer was decreased dramatically.At the late stage(100 days),the effect of nitrogen addition on microbial PLFAs was consistent with that at the early stage.The abundances of total,bacterial,and fungal^(13)C-PLFAs were remarkably increased in the anaerobic layer.However,the abundance of^(13)C-PLFAs in the micro-aerobic layer showed no significant response to nitrogen addition.During the incubation,the content of NH~+_4-N in the anaerobic soil layer was higher than that in the micro-a

关 键 词：稻田土壤 微氧层 还原层 土壤有机碳 水稻秸秆 氮素添加 磷脂脂肪酸(PLFAs) 

分 类 号：X171[环境科学与工程—环境科学]