Effect of Reclaimed Water Irrigation On Soil Physico-Chemical, Yield Attributes and Chemical Composition of Wheat (Triticum austivum L.), Cowpea (Vigna unguiculata L.) and Maize (Zea mays L.) Plants in Arid Regions.

A field experiment was conducted for 12 months (2010-2011) in Oman to study the effects of treated wastewater (reclaimed water). Plots with sandy loam texture soil were irrigated with three different water types: groundwater (GW), desalinized water (DW), and reclaimed water (RW). The design was RCBD with six replications. The three different water types were used as the treatments. Wheat (Triticum austivum L.) was used in the first period followed by cowpea (Vigna unguiculata L.) and then maize (Zea mays L.). Soil samples were collected prior to planting and after harvesting each crop at 4 depths. All data were subjected to analysis of variance (ANOVA) and the LSD at p<0.05 was performed to compare means. The results revealed significant differences among the water type treatments with respect to most growth and yield parameters and water use efficiency (WUE) (kg grain/ ha) of wheat. The wheat grain yield was superior in RW (4.53 t/ha) in comparison to DW and GW. The cowpea plant showed significant differences in respect to all traits under study except the dry forage yield (t/ha). For maize, the plants irrigated with RW gave the highest fresh (35.87 t/ha) and dry (12.46 t/ha) yield as well as WUE (1.19 kg dry/ m³). Significant differences were observed among the water types and harvest timing in respect to soil salinity.  Most of the heavy metals were not detected because of their scarcity in the soil.  It can be concluded that the use of reclaimed water irrigation increased the yield of wheat, cowpea and maize, however it did not affect the chemical composition those crops. The soil physical and chemical characteristics were in temperamental status, i.e. decreasing with time (e.g. Salinity and N %) and increasing after each harvest (pH, TOC % and other microelements).