Processes and influencing factors of organic phosphorus mineralization in various wetland soils in the Pearl River estuary, China

Organic phosphorus mineralization of various wetland soils from the Pearl River estuary were investigated using laboratory incubation experiments. Eleven kinds of soils from the three types of wetlands in three replicates were incubated under constant temperature and soil moisture in incubators under aerobic conditions. The physical and chemical properties, net phosphorus mineralization and net phosphorus mineralization rates of wetland soils were analyzed to reveal the processes and influencing factor of soil phosphorus mineralization. Our results showed that net phosphorus mineralization rates of wetland soils ranged from -126.47 to99.7675mg·kg-1·d-1. The net mineralization rate of soil phosphorus fluctuated in the first 15 days of cultivation, and gradually approached to 0 in the following period. The net mineralization rates of organic phosphorus in reclaimed wetland soils became stable in a short period of 15 days, and that of ditch wetland soils need a long time of 25 days. The mineralization rates of organic phosphorus in rural and urban river soils got a fluctuation in the whole incubation period, and spent 40 days to get stable. Among these studied wetlands, organic phosphorus mineralization in urban river wetland soils exhibited the most effective fixation, while the rates of net phosphorus mineralization in reclaimed wetlands showed a weak fluctuation. The net mineralization rates of organic phosphorus in constructed wetlands had no obvious change and approached to 0. The net mineralization rates of soil phosphorus had got a negative relationship with w(SOM), w(TC), w(TN), w(TH), w(TP) and water content (P <0. 01), and and no significant correlations were observed between net phosphorus mineralization rates with pH and MBC (P>0.05). The findings of this study can provide a theoretical guidance for the conservation and management of coastal wetlands.