الملخص الإنجليزي
Many arid and semi-arid countries became increasingly scarce in water resource and planners were forced to consider any sources of water which might be used economically and effectively to promote further development. At the same time, with population expanding at a high rate, the need for increased food production is apparent. Many countries have included treated wastewater reuse as an important dimension of water resources planning. Some countries like Oman have a national policy to reuse all treated wastewater and have already made considerable progress towards this. It is generally accepted that treated wastewater use in agriculture is justified on agronomic and economic grounds but care must be taken to minimize adverse health and environmental impacts. The purpose of this study is to show results of a project done at SQU farm using treated wastewater to irrigate wheat crop by drip and furrow bed irrigation systems.
The traditional surface irrigation system such as furrow remains the most common irrigation technique covering most of the agricultural area in Oman. The system has low water use efficiency and enhances soil erosion if not properly managed. The furrow system can be modified and improved to a level that can increase the efficiency and save much water.
The experiment was conducted in plots of loamy soil of 7.5 m2 each during the season 2010/2011 in the Agricultural Experimental Station of Sultan Qaboos University in the Sultanate of Oman. Each plot had either a drip irrigation system or furrow bed of 60 cm width. The design was complete block design with three treatments 1) water source: freshwater and treated wastewater; 2) irrigation method: furrow bed and drip; 3) wheat varieties: V1 Wadi Qurayat 302 (W.Q.S 302) and V2 (Sinien) and three replications. Wheat was sown and all required parameters for soil and plants were measured. Plants were irrigated daily by drippers and once every three days by furrows bed based on crop evapotranspiration value.
From soil salinity data, it was found that both methods added some salts to the root zone with less salts in furrow bed method due to leaching process during irrigation. However, no a significant differences (p<0.05) were found between both irrigation TV methods. Plant growth was better with tertiary treated wastewater and almost in all growth parameters compared to freshwater, probably due to increased nutrients value. Wheat irrigated by drip system gave lower biological yield compared to furrow bed irrigation. Generally, all measured data collected from both irrigation methods didn't show any significant difference (p<0.05). Water productivity (Kg/mo) data gave higher results with furrow bed compared to drip method. Drip irrigation could be better in reducing evaporated water whereas furrow bed is favorite method in getting good yield with less expenses and high productivity.
The study concluded that both fresh and tertiary treated wastewater irrigation water gave high production of wheat yield. Although, tertiary treated wastewater could add some salts, it has some nutritional values compared to fresh water that increase the wheat production. Using modified furrow bed irrigation system as alternative technique for traditional furrow method showed good results compared to drip system in term of cost and yields. It gave insignificant difference in salt accumulated in the root zone. For plant parameters, there were almost similar values with insignificant difference between both irrigation methods. Water productivity was the best indicator for the efficiency of both methods. Furrow bed method gave better value than drip system in all irrigation water when initial water was subtracted. This finding could be a good indicator for replacing furrow with furrow bed method.
