Dynamics of soil microbial biomass and dissolved organic carbon and nitrogen under flooded condition

With reddish yellow soil (RYS) and alluvial purple soil (APS), the two typical paddy soils in the Dongting Lake floodplain of China as test soils, an incubation test was conducted at 25 degrees C to study the dynamic changes of soil microbial biomass and dissolved organic carbon and nitrogen under flooded condition. Three treatments were installed, i.e., control (CK), ammonium sulfate (N), and rice straw powder plus ammonium sulfate (S-N). The results showed that during incubation, soil microbial biomass carbon (SMBC), soil microbial biomass nitrogen (SMBN), soil dissolved organic carbon (SDOC), and soil dissolved organic nitrogen (SDON) reached their maximum initially, decreased thereafter, and tended to be stable. After amending the substrates to the two soils, the averages of SMBC to soil total carbon, SMBN to soil total nitrogen, SDOC to soil total carbon, and SDON to soil total nitrogen were 2% - 3%, 2% - 3%, 1% or so, and 5% - 6%, respectively. In the two soils, the peak values of SMBC in treatment N an