Consumption potential of N2O and its influencing factors in paddy soils with different parent materials
Soil is a source and sink of N2O and can consume N2O under flooded and anaerobic conditions.Long-term flooding of paddy soil provides a favorable environment for N2O consumption,thereby reducing N2O emissions.N2O emissions from paddy soils have been studied extensively,but research on the N2O consumption capacity of paddy surface soil and its relationship with environmental factors is still lacking.In this paper,three types of paddy surface soils developed from quaternary red soil(loam,L),lake sediment sand(sandy loam,SL),and alluvial soil(silty clay loam,SCL)were selected to study their N2O consumption capacity using a microcosm experiment(60%soil mass water content and anoxic conditions).Air-dried soils collected from 5 cm in depth were treated with N2O addition(N2O)or helium addition(control)and incubated for 96 h at 28℃.The dynamics of N2O and N2,as well as the changes in soil nutrients during cultivation were monitored.N2O total consumption and N2 production were quantified to explore the consumption capacity of N2O of the three types of paddy soils and their related factors.The paddy surface soils consumed 95.01%-99.92%of the N2O in 5 cm soil depth,and the amount of N2O reduced to N2 was 64.50%-83.64%of the total N2O consumption.This indicated that different paddy soil had strong N2O consumption capacity under flooded and anoxic states.There were significant differences in the N2O consumption among the three soil types.The dominant factor affecting the N2O consumption of SL soils was the soil sand content,with a significant linear correlation(R2=0.964,P=0.000).Soil clay,silt,and pH were the main environmental factors affecting N2O consumption in SCL soils,and soil clay was significantly linearly related to its consumption(P<0.05).Soil available potassium and the increment of ammonium nitrogen was the main factor affecting the consumption of N2O in L soils.There was a significantly positive correlation between consumption and available potassium(P<0.01).Results showed that soil dissolved organic carbon,soil texture,and soil available potassium were important environmental factors affecting N2O consumption in paddy soils.The dominant factors varied for different soil types,which could provide an important reference for regulating N2O emissions from paddy fields.
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