Properties of arid soils irrigated with treated sewage effluent groundwater in Riyadh region, Saudi Arabia [electronic resource].

Includes references.

A study was conducted to find out the effect of 20 years irrigation with groundwater and treated sewage water (TSE) on some properties of calcareous soil. The study was carried out at three different sites irrigated with both water types and followed during four seasons. Results revealed that EC of groundwater (2.25dS m-1) was significantly higher than TSE and consequently led to increase soil salinity among different sites and seasons. Soil irrigated with groundwater contained significantly higher quantities of Ca2+, Mg2+, Na + and K+ cations and sulfate anion than soils irrigated with TSE. Both irrigation waters had a very low amount of NH4-N, NOr N, Fe, Mn, Zn, and Cu, which below the levels recommended for water quality. The present study demonstrates that after twenty years of using groundwater for irrigation of soils at Riyadh region, a major impact on soil salinity took place showing an inhibitory effect on soil microbial populations. Contradictory to that, treated sewage effluent did not show any deleterious effects on soil properties but led to increase many of useful biological processes specially which play an important role in soil fertility such as nitrogen fixation and nitrification. The minor effect on denitrifiers and sulfate-reducers may be attributed to the texture of soil in this region where anaerobic conditions is not prevalence. Results indicated that treated sewage effluent could be used for agricultural purposes as groundwater. The present study suggests to reuse treated sewage effluent in a large scale in Saudi Arabia for irrigation of woody trees or forest.

Summary in Arabic.

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