Variability of Physical and Chemical Properties of West Mesa Soils Irrigated by Industrial Effluent.

Knowledge of soil variability is useful for designing site specific soil management practices especially for those affected by anthropogenic activities. The objectives of this study were to determine the variability of soil physical and chemical properties due to the application of municipal and industrial wastewater in the West Mesa land application site and to group these soil properties into few principle components. Bulk and loose soil samples were collected from two wastewater irrigated and one unirrigated fields and analyzed for various physical and chemical properties. Variability in soil properties was identified by coefficient of variation (CV) as the indicator and a property was ranked as least (CV < 0.15), moderate (0.15< CV<0.35) or most (CV > 0.35) variable using the criteria proposed by Wilding (1985). Nitrate (NO₃^-), chloride (Cl), sodium adsorption ratio (SAR), hydraulic conductivity (K_s), sodium (Na⁺), exchangeable sodium percentage (ESP) and electrical conductivity (EC) were observed most variable in the irrigated plots at 0-20 cm depth. Principle Component Analysis (PCA) grouped 16 soil physical and chemical properties into five components named soil salinity, soil sodicity, water transmission, soil texture and water storage at 0-20 and 20-40 cm depth in the irrigated plots as well as for the pooled data from all three plots. The discriminant analysis of the principle components also identified the soil salinity and sodicity factor as the most discriminating factor. ESP and SAR were identified as the most dominating soil attributes for all the data sets; therefore this factors should be monitored over time in the west mesa land application site. As the attributes related to soil salinity and sodicity were most variable with mean EC and SAR of 1.31 dS m^-1 and of 19.17 respectively in the irrigated plots, it is necessary to initiate management strategies on controlling soil salinity and sodicity in the West Mesa land application site.