Evaluation of Quality of Irrigation Water in Different Soils

Abstract

A Iysimeter study using one quality of irrigation water (SAR =14.16, BC x 106,=2250 and RSC=S.88 m.e/l) and different textured soils was carried out from October, 1958 to April 1966 at Indian Agricultural Research Institute, New Delhi. Regression equations and type of relationships between number of irrigation and total soluble salts (%), pH., degree of sodium saturation and degree of dispersion were worked out. The same quality of instigation water used OD different textured soils has resulted differently. Heavy textured soils (predominantly montmorillenitic) showed more of salinity hazard as compared to kaolinitic and illitic light textured soils, whereas the reverse was the case for sodium hazard; 'The light textured soils developed sodic conditions and heavy textured soils reached to marginal values only with the use of this quality of irrigation water. It was predicted that Coimbatore and Guntur soils will be saline after 100 and 135 irrigations respectively. The salinity hazard seems to be determined by the low permeability of soils and the sodium hazard seems to be governed by the inverse ratio law. According to that lower cation exchange capacity soils have a higher sodium adsorption capacity and hence high sodium hazard. The soil factors like texture, cation exchange capacity. permeability, calcium carbonate, etc., should be considered for evaluation 'of irrigation water quality.