Soil bacterial communities have a pronounced role in processeswith environmental importance such as organic matter degradation and nutrientrecycling. Many anthropogenic practices contribute organic matter to the soil,including agricultural irrigation with treated wastewater (TWW). This practice,continuously increasing in arid and semi-arid regions, is essential for theoverall water management of many countries. However, the effect irrigation withTWW on soil microbiology is practically unknown.
The long term effect of TWW was measured during severalyears of different field applications, using both advanced molecularmicrobiology techniques and geochemically important enzymatic assays. Themultiannual results show that the bacterial community changed in compositionduring the period of irrigation with TWW. However, during the rainy season thecommunity returned to a “baseline” composition, similar to that of freshwater(FW) irrigated controls. In correspondence to the changes in composition, theactivities of the TWW irrigated soils increased during the irrigation periodbut returned to similar or lower level than in the FW control.
