Sorption of labelled phosphate by a vertisol and an alfisol of the semi-arid zone of India

Sahrawat, K L and Warren, G P (1989) Sorption of labelled phosphate by a vertisol and an alfisol of the semi-arid zone of India. Fertilizer Research, 20 (1). pp. 17-25. ISSN 0167-1731

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Adsorption isotherms for total adsorbed phosphate and isotopically exchangeable phosphate were measured for typical examples of a Vertisol and an Alfisol, occurring in close proximity at the ICRISAT centre. For each soil, the relationships of exchangeable P and total adsorbed P with phosphate solution concentration were described well by the Freundlich isotherm. Neither of the soils adsorbed significant amounts of P in a non-exchangeable form. The Vertisol had a higher capacity and buffer power for phosphate sorption, implying a lower response to fertilizer P. However, all adsorbed P remained in forms labile to 32P, equilibrated for 22 h, so that for equal amounts of CaCl2 extractable P there was more labile P in the Vertisol. In the absence of added P, the data suggested that the Vertisol maintained a greater level of dissolved and labile P. These observations are in accord with the results of field experiments, where larger applications of P may be required in Vertisols, compared with Alfisols, to achieve the same yield response, but that P is more freely available crops grown in Vertisols than is suggested by chemical extraction methods for available P

Item Type: Article
Subjects: Others > Soil Science
Depositing User: Mr B K Murthy
Date Deposited: 17 Nov 2011 03:36
Last Modified: 02 Jan 2012 09:13
Official URL:
Acknowledgement: UNSPECIFIED
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