Dynamics of dissolved organic carbon (DOC) leaching in meadow marsh soil and related affecting factors

In this paper, an incubation test with soil columns was carried out for 35 days to study the dynamics of DOC leaching from the organic layers (2 approximately 13 cm) of two meadow marsh soils, and the correlation of DOC release with soil respiration, NH4+ formation, and leachate pH. The results showed that in the first week, DOC release presented a fast decrease, and then held on a steady level, which could be well described by one order exponential equation (R2 > 0.96, P < 0.05). During 35 days incubation, the cumulative release of DOC from two test soils was 210.9 microg C x g(-1) and 506.58 microg C x g(-1), and the cumulative emission of CO2 was 679.64 microg C x g(-1) and 455.54 microg C x g(-1), respectively. It was suggested that in the course of incubation, the lower DOC release might be related to the microbial carbon limitation because of the greater CO2 production rate. A significantly positive correlation was found between DOC release and NH4+ formation (rXI = 0.886, P