Influence of dissolved organic matter on transformations of carbon and nitrogen in Paddy soils in subtropical China

Dissolved organic matter (DOM) is considered important in the transport and supply of carbon (C) and nitrogen (N) to microorganisms and has a major role in decomposition of soil organic matter. However the contribution of DOM to microbially mediated C and N transformations in paddy soils is not quantified. Laboratory incubation was conducted to investigate the relationship between DOM and carbon and nitrogen mineralization of paddy soils in subtropical China. The results showed that the cumulative mineralization of soil organic carbon decreased significantly 11.4%～20.8% with an average of 15.4% and soil organic nitrogen decreased 16.4%～22.9% with an average of 19.2% after DOM removed. The effects of DOM removal on mineralization of soil organic carbon were distinct in the prophase of incubation. This data illustrate that whilst DOM is a small component of the soil OM, it plays a significant role in mineralization of carbon and nitrogen within these agricultural soils.