Abstract

Cultivation of rice under different moisture levels warrants a revision of present mathod of soil analysis for phosphorus availability in various soils. In a greenhouse study three different groups of soils were utilised and IR 22 rice was grown under three moisture regimes viz., submergence at 5 cm depth, near field capacity and wetting and. drying. Soil samples were collected at the time of tillering, flowering and at harvest and analysed for available-P, using the following extractants (1) Olson's, (ii) Bray No.1. (ii) 0.01 M CaCl, and (iv) water. The initial soils were fractionated for various forms of P. Plant uptake of P was estimated after wet digestion and all these were correla- ted. Bray No. 1 extractant for red and black rice soils, while Olsens/Bray No. 1 for alluvial rice soils may form better indices of P availability.

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