Sustainable use and management of non-conventional water resources for rehabilitation of marginal lands in arid and semiarid environments

Land and water are the most basic resources for the food production systems. However, the looming water scarcity is threatening the sustainability of food production systems and is causing the food security challenges. Crop production on marginal and degraded lands using non-conventional water resources may help achieve the food security for the future generations. Non-conventional water resources (NCW), viz. saline water, wastewater and greywater, can be used for food production systems after proper treatment for the rehabilitation of marginal and degraded lands. In this review, experiences and perspectives of use of NCW in the Middle East and North Africa (MENA) region are discussed. The availability of NCW, their quantity and potential utilization in agriculture, landscaping, and forestry have been highlighted. Apart from Saudi Arabia, Oman, United Arab Emirates (UAE), Kuwait, Qatar and Jordan, wastewater treatment facilities are limited in the MENA region. However, consumption is increasing due to population increase. The changes in soil physical, chemical and biological characteristics, with the use of untreated wastewater, are also elaborated. The pragmatic strategies for NCW treatments including desalination, wastewater treatment, reuse of agricultural drainage water, groundwater extraction and rainwater collection have also been described. Here we reviewed that, (i) Legislation should be done to encourage farmers to use NCW and to grow crop species (safflower, sorghum, millet, carrots, radish, cucumber, tomatoes, eggplant, lettuce) which accumulate relatively very low amounts of metals in their edible parts, especially in pre-urban areas. (ii) Water treatment technologies should be advocated and implemented for the use of NCW. (iii) The NCW reuse should be promoted as an integral component in every country's national development strategic plan. Safe reuse of NCW has great potential, however, that can be effectively used through wise resource planning, and environmental management and financing arrangements.