稻田土壤N2O还原潜力的影响因素OA

The ecosystem of paddy fields is a primary contributor to N2O emissions within agricultural land,and studying the N2O reduction potential in paddy fields is of great significance for reducing N2O emissions and mitigating the atmospheric greenhouse effect.In this experiment,six typical paddy field soils from Jiangsu Changshu,Helongjiang Jiansanjiang,Jiangxi Yingtan,Sichuan Ziyang,Hainan Sanya and Guizhou Guiyang were selected for anaerobic cultivation to study the differences in N2O reduction rates and copy numbers of N2O reductase genes nosZ Ⅰ and nosZ Ⅱ in the plough layer of paddy fields,as well as their key influencing factors.The results showed that dissolved organic carbon(DOC)con-tent in the tested paddy soils ranged from 9.52 mg/kg to 61.21 mg/kg,which had a higher coefficient of variation than the total organic carbon content.The soil N2O reduction rate in paddy fields showed significant regional variation,and the aver-aged N2O reduction rate in Changshu paddy fields was 28.55 μg/(g·d),which was 5.9 times higher than that in the Yingtan paddy fields.Correlation analysis found that there was a significant positive correlation between the N2O reduction rate in paddy fields and soil DOC content.Quantitative PCR results showed that the copy numbers of N2O reductase genes nosZ Ⅰ and nosZ Ⅱ in the six paddy soils were 0.90× 107-9.09× 107copies/g and 1.01×107-6.53× 107copies/g,respectively.The copy number of gene nosZ Ⅰ was significantly and positively correlated with the N2O reduction rate in paddy fields,while the copy number of gene nosZ Ⅱ did not reach a significant level.Moreover,N2O net emission rate during the denitrification process was sig-nificantly positively correlated with the N2O reduction rate in paddy fields.This results suggested that the active carbon con-tent was an important factor in the process of N2O reduction in paddy fields,and N2O reduction process in the tested paddy fields might be mainly driven by nosZ Ⅰ type microorganisms.