摘要
土壤中碳(C)和氮(N)等底物的可利用性决定着微生物生长代谢,同时影响土壤胞外酶活性.为探讨土壤酶活性对土壤原有有机质变化的响应,本试验选取了长期定位试验田的4种施肥处理水稻土[无肥对照(CK)、单施化肥(NPK)、有机肥+化肥配施(OM)和秸秆还田+化肥配施(ST)],通过0、 4、 8和12个月的分段培养获取了具有不同可利用性C、N含量梯度的土壤,分析参与土壤碳氮转化过程的关键酶β-1,4-葡萄糖苷酶(BG)和β-1,4-N-乙酰氨基葡萄糖苷酶(NAG)活性与可溶性有机碳(DOC)、铵态氮(NH4^+-N)、土壤微生物生物量碳(MBC)和微生物生物量氮(MBN)含量的关系.结果表明,OM和ST处理对土壤中DOC含量的提高更显著(P<0.01),是CK和NPK处理的2~3倍.NPK、OM和ST处理的MBC含量、BG和NAG酶活性高于CK处理.所有施肥处理中,随着可利用性底物(DOC和NH4^+-N)含量的升高,BG和NAG活性整体呈稳定或下降趋势,MBC和MBN含量变化趋势与BG和NAG相同.施肥处理和培养时间以及二者的交互作用极显著影响(P<0.01)土壤DOC、NH4^+-N、MBC和MBN的含量.回归分析显示, OM处理MBC/MBN值与DOC/NH4^+-N值之间正相关(P<0.05);ST处理的ln(BG)/ln(NAG)值和DOC/NH4^+-N值之间负相关(P<0.01),这表明稻田土壤可利用性底物浓度是影响胞外酶活性的关键因子,且微生物量的碳氮计量比受控于土壤中底物的碳氮计量关系.该结果对深入研究稻田土壤中胞外酶活性变化规律,调节稻田土壤碳氮平衡,提高稻田土壤肥力具有一定指导意义.
The availability of carbon(C),nitrogen(N),and other substrates in soil determines the growth and metabolism of microorganisms and affects the activity of extracellular enzymes.To study the activities ofβ-1,4-glucosidase(BG)andβ-1,4-N-acetylglucosaminidase(NAG)in response to C and N availability,samples that underwent four treatments—non-fertilization(CK),chemical fertilizer(NPK),combination of organic manure and chemical fertilizer(OM),and mixture of straw and chemical fertilizer(ST)—were collected from long-term fertilization paddy soil and incubated for 0,4,8,and 12 months to obtain soil with different C and N availability gradients.The results showed that the dissolved organic carbon(DOC)content of OM and ST treatment samples was 2-3 times higher than that of CK and NPK treatment samples.With the increase of DOC and ammonium(NH4^+-N)contents,the activities of BG and NAG and the contents of microbial biomass C(MBC)and N(MBN)showed no increase during incubation within each treatment.Fertilization treatments,incubation time,and their interaction are crucial factors varying the contents of DOC,NH4^+-N,MBC,and MBN among different fertilization treatments(P<0.01).There was a positive correlation between MBC/MBN and DOC/NH4^+-N of OM treatment(P<0.05)and a negative relationship between ln(BG)/ln(NAG)and DOC/NH4^+-N of ST treatment(P<0.01),indicating that the availability of substrates played a key role in the potential activity of extracellular enzymes in paddy soil,and the carbon-nitrogen ratio of microbial biomass was controlled by the C/N stoichiometry of substrates in soil.The results have a certain guiding significance for further study on the variation of extracellular enzyme activity in paddy soil,regulating the balance of carbon and nitrogen,and improving the fertility of paddy soil.
作者
宁玉菲
魏亮
魏晓梦
祝贞科
袁红朝
葛体达
吴金水
NING Yu-fei;WEI Liang;WEI Xiao-meng;ZHU Zhen-ke;YUAN Hong-zhao;GE Ti-da;WU Jin-shui(Key Laboratory of Subtropical Agriculture Ecology,Institute of Subtropical Agriculture,Chinese Academy of Sciences,Changsha 410125,China;University of Chinese Academy of Sciences,Beijing 100049,China)
出处
《环境科学》
EI
CAS
CSCD
北大核心
2020年第6期2852-2860,共9页
Environmental Science
基金
国家自然科学基金项目(41430860,41771334)
湖南省自然科学基金优秀青年基金项目(2019JJ30028)
湖南省自然科学基金创新群体项目(2019JJ10003)。
关键词
胞外酶活性
底物可利用性
碳氮计量比
水稻土
长期施肥
extracellular enzyme activity
substrate availability
C/N stoichiometry
paddy soil
long-term fertilization
