Muscat: A study on maximising the use of reclaimed water or tertiary-treated wastewater for farming seasonal crops such as wheat, maize and cowpea in the Al Batinah region of the Sultanate shows that this practice will prevent the disposal of reclaimed water into the sea and minimise the stress on groundwater zones in the country.
This research was compiled by Saif Ali Salim Al Khamisi, head of Field Crops Research at the Directorate General of Agricultural & Livestock Research of the Ministry of Agriculture & Fisheries (MoAF), as part of his PhD programme at the Sultan Qaboos University (SQU).
Saif Al Khamisi, who joined SQU in the year 2009 to pursue a PhD, conducted extensive studies on maximising the use of reclaimed water for crop production in arid regions, which qualified him to successfully defend his thesis on this subject.
He stated: "To combat water scarcity and the conservation of water resources, the Sultanate is planning to transfer reclaimed water from different sewage treatment plants (STPs) in the Muscat governorate to the agricultural lands in Al Batinah governorate. This region accounts for more than 60 per cent of the total agricultural land area in Oman. This is because Muscat alone produces 80,000 cubic metres of reclaimed water per day, and only 54 per cent of it is utilised for irrigating the gardens and trees along the highways in Muscat."
Quoting his own PhD thesis, Al Khamisi noted that over 55 sewage treatment plants in Oman's different governorates produce more than 100 million cubic metres of reclaimed water per year, which can be used for irrigation.
"Agriculture in Oman contributes to partial food sustainability and forms an important part of rural livelihood. It accounts for 3.2 per cent of the GDP in Oman, of which, fruits comprise 53 per cent, followed by perennial forages (30 per cent), vegetables (11 per cent), and field crops (6 per cent)."
In his study, he goes on to say if Oman decides not to use expensive water from desalination plants or fresh groundwater for irrigation, then the maximum area that can be irrigated solely with reclaimed water will be determined on a day when the demand for evapotranspiration is at its maximum level.
On other days, there will be a surplus of reclaimed water, unless the conjunctive water management strategy of supplementing reclaimed water with groundwater is formulated.
If a conjunctive water management strategy is adopted, then the area dedicated to crops may be increased, and groundwater withdrawal can be reduced.
Al Khamisi's study focused on the use of reclaimed water, supplemented by groundwater, by identifying short-season crops and using the land area for cultivating such crops as a variable.
The study found that by using reclaimed water conjunctively with ground water, agricultural land can be increased from 1,353 ha to 3,781 ha.
Of the total irrigation requirement of 24.24 million cubic metres, 57.6 per cent could be met with reclaimed water and 42.4 per cent could be met with groundwater.