Small scale stratification of microbial activity parameters in Mediterranean soils under freshwater and treated wastewater irrigation

Using treated wastewater for agricultural irrigation is a common practice in many water-scarce countries. Apart from the beneficial effects associated with the nutrient load and organic substrates, some negative effects on soil properties, such as increased water repellency or priming effects have been observed. The objective of this study was to determine if negative effects are associated with differences in microbial activity parameters. Soil samples were collected from three sites in Israel (IL) and Palestine (PA): (i) a lysimeter experiment near Lachish (IL) with three soils irrigated with four different water qualities; (ii) a long-term field experiment in a citrus orchard (Batsra, IL) irrigated with fresh water (FW) and treated wastewater (TWW), and (iii) an arable field experiment with also FW and TWW irrigation (Gaza, PA). Samples were collected from 0 to 5 (top-crust) and 5–20 mm (sub-crust) and analyzed for biological and chemical properties.