Characterization of Irrigated Soils with Different Water Sources in Kanakapura Taluk of Ramanagara District, Karnataka, India

Abstract

Irrigated agriculture relies on having a sufficient supply of good quality water to sustain soil health, crop yield, product quality, public health and environment. In this research, different water sources like dam, lake and borewell were assessed during the year 2023-24 since these waters are being used in the Kanakapura taluk for irrigation purpose. Ten water samples from each water sources and ten surface soil samples from each water sources irrigated soils were analysed and compared with rainfed soils. The results of irrigation water sources showed that biological oxygen demand values were within permissible limit of 30 mg L-1 but chemical oxygen demand values were elevated in the lake (74-258 mg L-1) and dam (228-256 mg L-1) waters. The pH of all water sources (6.71-8.50) was found suitable for irrigation. These waters had high amount of total soluble salts (EC: 523-1623 µmhos cm-1) and fell under medium to high salinity hazard classes. The borewell waters showed high to very high alkalinity hazard (RSBC: 5.4-11.20 meq L-1) compared to lake and dam waters. All water samples exhibited excellent SP (<20%), SR (<1) and SAR (<10) values indicating negligible sodicity hazard. The coliforms, total bacteria and fungi counts were comparatively high in lake and dam waters. The soils irrigated with different water sources showed relatively lower bulk density (1.31-1.46 Mg m-3) and higher water holding capacity (37-44%) but it was vice versa in rainfed soils. Irrespective of irrigated or rainfed cultivation, the soils were neutral to moderately alkaline in reaction (pH: 6.85-8.31) and non-saline in nature (EC: 0.06-0.39 dS m-1). The lake water irrigated soils were found to be relatively more fertile and contained higher microbial population. Overall, the lake water irrigation had the most positive impact on soil health as compared to other water sources tested.