The long-term impact of irrigation on a Mediterranean sandy soil
irrigated with Treated wastewater (TWW) since 1980 was evaluated. The
main soil properties (CEC, pH, size distribution, exchangeable cations
and chloride, hydraulic conductivity) as well as the organic matter and
Cu, Cr and Pb speciation in an irrigated soil and a non-irrigated
control soil at various soil depths were monitored and compared during a
2 years experiment. In this first part, the evolution of the
physico-chemical soil properties was described. The irrigation with TWW
was beneficial with regard to water and nutrient supplying. All the
exchangeable cations other than K(+) were higher in the irrigated soil
than in the reference one. A part of the exchangeable cations was not
fixed on the exchange complex but stored as labile salts or in
concentrated soil solution. Despite the very sandy soil texture, both
saturated and unsaturated hydraulic conductivity exhibited a significant
diminution in the irrigated soil, but remained high enough to allow
water percolation during rainy periods and subsequent leaching of
accumulated salts, preventing soil salinization. In the irrigated soil,
exchangeable sodium percentage (ESP) exhibited high values (20% on
average) and the soil organic C was lower than in the reference. No
significant effect was noticed on soil mineralogical composition due to
irrigation. (C) 2010 Published by Elsevier Ltd.