The effect of irrigation water quality on soil properties under center pivot irrigation systems in central Saudi Arabia

A field experiments were conducted for three growing seasons (2007 to 2009) at five different sites of soil types and salinity levels. Five different ground water qualities were used to irrigate five fields each with area of 50 to 54 hectares planted with wheat crop and the irrigation system used at each field was center pivot sprinkler system. The irrigated fields were located at different locations of Riyadh region in Saudi Arabia. The soil samples were taken at different depths (10, 20, 40, 60 cm) from the soil surface at the beginning of season 2007 and at the end of season 2009. The quality effect of irrigation water on each soil salinity at each depth was determined. The results showed that all irrigated fields have differed in salt concentration as indicated by soil electrical conductivity (ECe) values of the saturated paste extracts. The soil salinity in some fields decreased and increased in other soils, and the distribution of salts through the soil profile is highly correlated with the salinity of irrigation water and soil type. Saline water increased the soil salt content throughout the profile to a greater extent than nonsaline water. Thus, the salts accumulation in soil of field 4 and 5 was closely related to the salt concentration of irrigation water, and there was a progressive and significant increase in soil salinity values as the salinity of irrigation water increases. Also, the obtained results showed that the decrease or increase in soil salinity through the soil profiles for all fields occurred mainly at first season and slight increase in the following two seasons, and not with the increase of the number of seasons, and the soil salinity values remains closely the same and does not influenced by the prolonged use of low or high salinity waters for a number of years for all fields during the study. Water Resources Management VI 507 www.witpress.com, ISSN 1743-3541 (on-line) WIT Transactions on Ecology and the Environment, Vol 145, © 2011 WIT Press doi:10.2495/WRM110441