CHEMICAL CONSTITUENTS AND SUITABILITY STUDIES OF GROUNDWATER FOR IRRIGATION POURPOSES IN RANGPUR

Abstract

An investigation was carried out to assess the suitability for irrigationpurposes of 50 groundwater samples collected from different locations of Sadar Upazilla of Rangpur district. Analyses included pH, EC, TDS (total dissolved solids), cations (Ca2+, Mg2+ , Na+ , K+ , Cu2+, Mn2+ , Fe3+) and anions (HCO3 - , SO4 2- , PO4 3- and Cl- ). Several computed variables such as SAR (sodium adsorption ratio), SSP (soluble sodium percentage), hardness (HT), permeability index (PI), Kelly’s ratio, and potential salinity to evaluate the suitability of groundwater supply for specific uses. Some correlations and compositional relations were also evaluated. Almost all the water samples were within the recommended pH value for irrigation and had a great impact on crop production. According to Wilcox, 14 samples were excellent, 36 samples were good for irrigation purposes in respect to EC. For TDS all samples except seven samples were considered as ‘freshwater’ for irrigation.Based on SAR values, all samples were classed as ‘excellent’ categories for irrigation. On the basis of Ca, K, Fe and Cu, content the entire water samples can safely be used for irrigation and would not affect the soils. The SAR and SSP of all waters were under ‘excellent’ class. In the present study, some samples were considered ‘Hard’ while others were ‘moderately hard’ and few samples were ‘soft’ for irrigation usage. The results also provided data for water quality of groundwater resources of study region to match national and international standards for agricultural requirements.