Solubility of phosphorus in subtropical forest soils as influenced by low-molecular organic acids and key soil properties

Low phosphorus (P) solubility in soil limits primary productivity in terrestrial ecosystems worldwide. However, our understanding about drivers of soil P solubility is still incomplete. This study examined the levels of water soluble inorganic P (Pi) and organic P (Po) in soils under mature subtropical forests in China, and how they can be influenced by three low-molecular organic acids (LOAs, i.e. citric, malic and oxalic acids) and key soil properties (e.g. organic C concentration). Water soluble Pi (mean 0.05mgkg−1) and Po (0.32mgkg−1) in the soils studied were generally low, compared to in many other areas of the world. While all three LOAs significantly solubilized P from the soils studied as a whole, the solubilized amount varied greatly among soils and also varied largely with the type of LOA and P forms. Solubilized Po by the three LOAs were >2.5 times of the solubilized Pi. Soluble total P (Pi+Po) increased in the order of oxalic acid更多