ABSTRACT
Background Phosphorus (P) is one of essential macronutrients required for the normal growth and development of higher plants. Plant roots acquire P as phosphate (Pi), primarily in the form of H2PO4
-, from the soil solution [1]. Although total Pi is abundant in many soils, the available Pi in the soil solution is commonly 1 – 2 µM due to its binding to soil mineral surfaces and xation into organic forms [2]. Hence, P is one of the unavailable and inaccessible macronutrients in the soil [1]
and is often the most limiting mineral nutrient in almost all soils [2]. Among the fertility constraints to crop production in China, low Pi availability is the primary limiting factor [3]. Pi availability is particularly limiting on the highly weathered acid soils of the tropics and subtropics, in which free iron and aluminum oxides bind native and applied Pi into forms unavailable to plants [2,3]. erefore, Pi availability is often a major limiting factor for crop production in acid soils [2].
