Effects of dry sludge application on soil microarthropod communities in a reclaimed desert ecosystem

The ecological impact of dried sewage sludge addition to reclaimed soil was assessed by comparing soil microarthropod fauna (oribatid and collembolan populations) of sewage sludge treated plots with those of adjacent control plots. An Egyptian orchard of newly reclaimed soil cultivated with guava trees (sandy soil) at El Salheya region was selected for the present investigation. Sludge application was performed at three doses i.e. 1.6 ton/ha, 3.3 ton/ha and 6.5 ton/ha. Four replicates were conducted for each dose application through a one-year period (during the four seasons). Sludge application had a marked influence on some soil microarthropods but no influence could be detected on others. The intensity of the effect was strongly correlated to sludge doses. Also, a marked quantitative and qualitative influence could be observed on soil-bound mites. It was discovered that application of sludge up to 6.5 ton/ha over the period of a year to the reclaimed area produced a marked significant effect on the oribatid community. Scheloribates laevigatus, Epilohmannia c. cylindrica and Isotomina thermophila may serve as bioindicators to evaluate the role of sewage sludge application on the soil habitat.