Water Retention Characteristics of Some Vertisols of Rajasthan

Variation in water retention characteristics has been evaluated in Typic, Calcic, Petrocalcic and Sodic Haplusterts. Forty-one, 21.9 and 6.5 per cent higher water retention have been noticed in the surface horizons of Sodic, Calcic and Petrocalcic Haplusterts, respectively, at 0.03 MPa. However, at 1.5 MPa, the higher water retention has been noticed only in Sodic Haplusterts. Exchangeable sodium and lime accumnlation at 0.03 MPa while sodium charged smectite at 1.5 MPa are accounted for the variations. Calcic and Petrocalcic Haplusterts have recorded 16 to 35 per cent higher available water capacity (AWC) than their Typic counterpart while Sodic Haplusterts maintain only 5 to 17 per cent increase in the corresponding horizons as compared to Typic. In contrast, plant available water capacity (PAWC) is recorded highest in latter while it is restricted in former due to presence of calcic and petrocalcic horizons with minimum water retention at both the suctions.