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

Abstract

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.