Organic amendments(OM)can profoundly affect soil nitrous oxide(N_(2)O)emissions via changing nitrogen(N)cycles.However,mechanistic insights into how nitrification inhibitors modulate the responses of soil N_(2)O emiss...Organic amendments(OM)can profoundly affect soil nitrous oxide(N_(2)O)emissions via changing nitrogen(N)cycles.However,mechanistic insights into how nitrification inhibitors modulate the responses of soil N_(2)O emissions to successive applications of OM are currently insufficient.In this study,we performed a laboratory experiment to examine N_(2)O emissions from a tropical vegetable soil subjected to six years of chemical fertilization(CF)and chemical fertilization combined with manure application(CFM)and evaluate the mitigation effectiveness of nitrification inhibitor dicyandiamide(DCD)under each management regime.Isotopocule mapping showed that bacterial nitrification and/or fungal denitrification accounted for 77.4%–88.5%of total N_(2)O production across treatments during the emission peak.The cumulative N_(2)O emissions from the CFM-treated soil were nearly 8-fold of those from the CF-treated soil.The CFM treatment stimulated N_(2)O production from bacterial nitrification and denitrification by increasing the abundance of genes linked to nitrifiers(ammonia-oxidizing bacterial(AOB)amoA and total comammox amoA)and denitrifiers(nirK,nirS,and qnorB),respectively.Importantly,DCD decreased cumulative N_(2)O emissions by an average of 73.3%,with better mitigation performance observed in the CFM-treated soil than in the CF-treated soil due to stronger inhibited nitrification and increased abundance of the nosZ gene,and altered bacterial community composition.The 16S rRNA sequencing further revealed that adding DCD to the CFM-treated soil resulted in declines in the abundances of bacterial phylum Actinobacteria and Chloroflexi that positively affected N_(2)O emissions;the opposite pattern prevailed for Gemmatimonadetes that negatively affected N_(2)O emissions.This study highlights the potential of manure application,when coupled with nitrification inhibitors,to achieve the dual goals of enhancing soil fertility and reducing environmental risk associated with N_(2)O emissions in tropical agricultural soils.展开更多
基金supported by the National Natural Science Foundation of China(Nos.42007098 and 32001209)the Major Science and Technology Plan of Hainan Province,China(No.ZDKJ2021008)+1 种基金the Natural Science Foundation of Hainan Province,China(Nos.320RC687 and 421QN0915)the Central PublicInterest Scientific Institution Basal Research Fund for Chinese Academy of Tropical Agricultural Sciences(Nos.1630042025001,1630042025011,and 1630042025012)。
文摘Organic amendments(OM)can profoundly affect soil nitrous oxide(N_(2)O)emissions via changing nitrogen(N)cycles.However,mechanistic insights into how nitrification inhibitors modulate the responses of soil N_(2)O emissions to successive applications of OM are currently insufficient.In this study,we performed a laboratory experiment to examine N_(2)O emissions from a tropical vegetable soil subjected to six years of chemical fertilization(CF)and chemical fertilization combined with manure application(CFM)and evaluate the mitigation effectiveness of nitrification inhibitor dicyandiamide(DCD)under each management regime.Isotopocule mapping showed that bacterial nitrification and/or fungal denitrification accounted for 77.4%–88.5%of total N_(2)O production across treatments during the emission peak.The cumulative N_(2)O emissions from the CFM-treated soil were nearly 8-fold of those from the CF-treated soil.The CFM treatment stimulated N_(2)O production from bacterial nitrification and denitrification by increasing the abundance of genes linked to nitrifiers(ammonia-oxidizing bacterial(AOB)amoA and total comammox amoA)and denitrifiers(nirK,nirS,and qnorB),respectively.Importantly,DCD decreased cumulative N_(2)O emissions by an average of 73.3%,with better mitigation performance observed in the CFM-treated soil than in the CF-treated soil due to stronger inhibited nitrification and increased abundance of the nosZ gene,and altered bacterial community composition.The 16S rRNA sequencing further revealed that adding DCD to the CFM-treated soil resulted in declines in the abundances of bacterial phylum Actinobacteria and Chloroflexi that positively affected N_(2)O emissions;the opposite pattern prevailed for Gemmatimonadetes that negatively affected N_(2)O emissions.This study highlights the potential of manure application,when coupled with nitrification inhibitors,to achieve the dual goals of enhancing soil fertility and reducing environmental risk associated with N_(2)O emissions in tropical agricultural soils.
