Abstract

                                Large tracts of red and black soils occur towards the South-east region of U. P. in Vindhyan range. As the demand for more food is increasing, these soil areas will have to be put under plough and in order to get more yield per acre a definite manuring schedule will have to be adopted. Before phosphate can be added to these soils, it will be necessary to have a first hand knowledge regarding phosphorus potentialities of these soils. Phosphorus exists in combination with Ca, Fe, Al and organic fraction of soils. Accordingly such forms as Ca-P, Fe-P, Al-P and organic bound P have been differentiated. For chemical characterization of soil phosphorus, a fractionation of soil phosphorus is necessary because the chemical nature of each form of soil phosphorus is a factor which determines their relative effectiveness for crop growth.

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