Research advance in soil phosphorus fractionations and their characterization by chemical sequential methods and³¹P-NMR techniques

Transformation of soil phosphorus (P) is an important part in P cycle in ecological system, which influences soil P availability for crops. Soil total P includes organic and inorganic P. Chemical sequential fractionation (CSF) methods with different chemical extraction solvents are often used to determine different forms of P in soils. Despite the extensive use of these CSF procedures, there are obvious shortcomings, e.g. less accurately distinguishing inorganic and organic forms of P. Nuclear magnetic resonance (NMR) can be used to identify exactly molecular forms of P in soils. Some reports of³¹P-NMR technique to study soil P forms and transformation were reviewed in this paper, and advances in the preparation process of soil samples and³¹P-NMR analysis parameters were summarized. Two-dimensional³¹P-NMR spectroscopy will be developed to improve P fractionation in quantification in soils.