Abstract

P is known to exist in organic and inorganic forms in soils. Among the various fractions of inorganic P, phosphates of aluminium, iron and calcium are considered to be important from the point of view of fixation and availability of P in soils. The rate and quantity of P that becomes soluble from these sources under various soil and environmental conditions determine the P status of a soil. Evidence is ample in literature to indicate that distribution and availability of P depend largely on the forms of soil P. Since the different forms of soil P have different solubilities, the forms and distribution pattern might give an indication about the availability of P in the soil. Though much work has been done on the chemistry and behaviour of P in acid soil, due attention has not been paid to soils of alkaline reaction. Therefore systematic investigations are considered necessary to gain an insight into the various phenomena of P behaviour in alkaline soils and the present work refers to a study with Tamil Nadu soils.

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