Fe and Al oxides are common chemical substances in soil,which participate in soil redox reactions,but their roles of different contents in carbon and nitrogen transformation in forest soil are still not well understood.In order to explore the effects and different roles of Fe and Al oxide content on soil carbon and nitrogen mineralization,subtropical forest soil was selected as the research object.Different amounts of Fe and Al oxide(Fe(OH)3:0,10,20,30,50,70 g·kg-1 and Al(OH)3:0,1,2,3,5,7 g·kg-1)were mixed with 50 g(based on dry mass)soil samples,and the indoor aerobic incubation was carried out at constant temperature.Greenhouse gas emission rate and cumulative emissions,DOC(dissolved organic carbon),inorganic nitrogen and nitrogen transformation rate were analyzed.The results showed that:1)after Fe oxide addition,soil DOC content decreased with the added levels,and the DOC content of 50 and 70 g·kg-1 treatment signifi-cantly decreased by 29.86%and 33.90%,respectively.The cumulative emissions of CO2 and CH4 were significantly positively correlated with Fe oxides added levels.And CH4 cumulative emissions was positively correlated with CO2 cumulative emissions but negatively correlated with DOC content.The increase of Fe oxide addition significantly promoted the soil net nitrification.When the addition amount was 10 g·kg-1,the net nitrification rate was 5.58 mg·kg-1·d-1,but the net nitrification rate reached 43.31 mg·kg-1·d-1 at 70 g·kg-1.The DON(dissolved organic nitrogen)content in-creased from 25.62 mg·kg-1 to 61.60 mg·kg-1 at a range of 0～20 g·kg-1,and then decreased from 62.01 mg·kg-1 to 12.74 mg·kg-1 at 30～70 g·kg-1.So,20～30 g·kg-1 Fe oxide may be the critical value affecting the decomposition and mineralization of organic nitrogen in soil.2)The addition of Al oxide had a weak effect on promoting soil carbon mineralization,and even inhibited CO2 emission.Al oxide addition did not significantly affect soil CH4 emission,DOC content and net nitro-gen mineralization,but DON content increased significantly by 92.47%～173.69%.In this study,the effects of Fe and Al oxides on N2O emissions were not found.In summary,Fe oxide can promote soil carbon and nitrogen mineralization,while Al oxides have relatively weak or inhibiting effects.
subtropical forest soilFe and Al oxidessoil carbon and nitrogen mineralizationgreenhouse gas
NETL
NSTL
万方数据
