Soil Characteristics and Agro-well Water Quality in Newly Developed Farmlands in Mahaweli System L-Ethawetunuwewa Block, Sri Lanka

Agro-wells are the most reliable water resource in newly developed farmlands in Mahaweli System L. However, water quality of agro-wells and its relationship with soil parameters in surrounding farmlands have not yet been investigated. This study was conducted to investigate agro well water quality, to explore its relationship with soil elements and to find out short-scale soil spatial variability of surrounding areas of agro-wells. Water samples were collected from 10 agro-wells located in the study area at three time points. Soil samples from surrounding farmlands of each agro-well were also collected. In addition, intensive soil sampling was done surrounding a selected agro-well to prepare short-scale spatial variability soil maps using Inverse Distance Weighting interpolation technique. Soil and water samples were analyzed for relevant chemical parameters. Correlation analysis was performed to investigate relationship between soil and water quality parameters. All water quality parameters except NO3 -N, K and Cd were within acceptable range. Potassium, Cd in all tested agro-wells and NO3 -N levels in 6 agro-wells have exceeded the maximum permissible level. Correlation analysis revealed a strong positive linear correlation between soil and water concentrations of NO3 -N (r = 0.83) Available Sulfur (r =0.81) and Ca (r =0.82). Natural short-scale spatial variability pattern of soil N, P, K in the studied area have been altered due to anthropogenic activities such as fertilizer applications.