Soil phosphorus composition determined by 31P NMR spectroscopy and relative phosphatase activities influenced by land use

Land use can alter the phosphorus (P) pool in soil. Understanding detailed P changes derived from different land uses is important for sustainable development of soil resources. However, soil P composition and phosphatase activities under different land uses in temperate regions remain widely unknown. Soils from four types of land use, including cultivated (Maize and Paddy) and uncultivated (Woodland and Fallow) soils, in the same region were selected to characterize soil P composition using solution 31P nuclear magnetic resonance (31P NMR) spectroscopy. Four soil phosphatase activities, acid phosphomonoesterase (AcP), alkaline phosphomonoesterase (AlP), phosphodiesterase (PD) and pyrophosphatase (PY), were also considered. The results showed that the proportions of dominated inorganic orthophosphate were higher in cultivated soils than in uncultivated soils, while the opposite trend was observed for organic orthophosphate monoesters and diesters. Generally, soil phosphatase activities were higher in uncultivated soils than in cultivated soils. The multivariate analysis indicates that soil P composition as well as phosphatase activity was significantly influenced by land use. The correlation analysis showed that soil AcP and PY activities were positively correlated with soil monoester and pyrophosphate, respectively, and were negatively correlated with soil available P.

► Cultivated soils dominated with Pi and uncultivated soils dominated with Po. ► Soil monoesters and diesters decreased under cultivated condition. ► Phosphatase activities were higher in uncultivated than cultivated soils. ► Monoester and pyrophosphate were positively correlated with AcP and PY.