增温和秸秆还田对黑土农田土壤氮素有效性和N2O通量的影响OACSTPCD

Soil nitrogen(N)transformation processes determine the capacity of soil N supply to plant.The soil N transformation rates are affected by temperature and substrate availability.However,we are still far from understanding how soil N availability and nitrous oxide(N2O)flux respond to warming and straw returning.We conducted a field experiment in a Mollisol cropland in North-east China.We measured soil N availability and N2O flux in the 0-20 cm soil layer by using ion exchange resin membrane(IERM)in situ and static chamber-gas chromatography.Our results show that neither warming nor straw returning has significant effect on soil N availability,but the sampling time has a significant effect on soil N availability.Straw returning significantly increases N2O flux;in July,warming and straw returning has a significant interaction on N2O flux.Under the un-warming condition,straw returning significantly increases N2O flux by 109%;but under the warming condition,straw returning reduces N2O flux by 2%.Warming,straw returning,and sampling time has significant interactive effects on N2O flux.Overall,this study helps to evaluate the effect of straw returning on soil N transformation under global warming in cropland ecosystems,which is essential to future research on N cycling in Mollisols.