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Getting the most from marginal water

Getting the most from marginal water

In situations of extreme water scarcity farmers in the Middle East are often forced to turn to marginal, poor quality water including waste, grey, and brackish water. However, utilizing these alternatives brings considerable environmental and health risks, and so strategies and inputs are needed to mitigate their negative effects.

Acknowledging the increasing dependence on marginal water, the Water and Livelihoods Initiative (WLI) is investigating how farmers can use brackish and saline irrigation water to raise their yields and improve their water productivity. In Egypt and Iraq the effectiveness of water treatments such as the application of additional nutrients and fertilizer is being investigated; and in Jordan, the initiative is exploring opportunities for promoting the use of household-level greywater treatment units.

Using brackish water in integrated food systems   

At the Wadi El-Nahroun research station, located in the western part of the Nile Delta, researchers are investigating whether water previously used for the production of tilapia fish can be enhanced with additional nutrients and utilized again for the irrigation of saline-tolerant crops such as sugar beet and barley.

Aquaculture is big business in Egypt – the country is the second largest producer of farmed tilapia in the world – so success could help secure vital water resources for crop production, potentially benefiting thousands of smallholder farmers. Related data regarding crop water requirements, applied water rates and plant performance are now being analyzed.

Applying fertilizer as a mitigating strategy

In Iraq, poor access to quality water is compounded by on-going instability and conflict, which disrupts freshwater supplies. This problem, which is affecting the initiative’s research station at Abu Ghraib, compels farmers to use brackish well water for irrigating crops. Given the potentially negative effects of using this water resource, researchers are investigating the following mitigation strategies: the impact of K fertilizers and compost fertilizers on potato yield; the resistance of pepper to brackish water using K fertilizer; and the resistance of cucumber to drought and brackish water through the application of cultar (Cytokine) hormones.

Fertilizers, irrigation water, and other inputs were applied at various rates and at different stages of plant growth. Results were encouraging. They include: 

  • Potato yields were 47 percent higher when 600 kilograms (kg) of K2SO4 per hectare (K2SO4/ha) was applied; and 58 percent higher when 400 kg of K2SO4/ha was applied.
  • Applying 10 tons per hectare (t/ha) of compost fertilizer and 3500 m3 of brackish irrigation water generated potato yields of 62 t/ha.
  • Applying K fertilizer significantly increased pepper yields – the best result being a 24 percent increase with the application of 420 kg of K2SO4.
  • Applying Cytokine hormones at a rate of 200 milligrams per hectare (mg/ha) and brackish irrigation water at a rate of 150 m3/ha resulted in cucumber plants demonstrating more resistance to drought. 

The results demonstrate that even when quality water is scarce, farmers can instead utilize poorer quality water and with the right combinations of inputs – additional nutrients, hormones, or fertilizers – maintain or even raise their crop yields. Scaled-up across wider areas, these interventions have the potential to benefit thousands of rural communities despite predicted declines in the availability of freshwater.

Using treated greywater for home gardens

In Jordan – currently ranked as the world’s second most water-scarce country – researchers are exploring the potential of using treated greywater in the household production of important food crops, including olives, grapes, almond trees and alfalfa. Facing population growth, an influx of refugees, and the detrimental impacts of climate change, the country needs an urgent solution to its water scarcity crisis to ensure sufficient water for agriculture and other competing sectors.

Greywater – wastewater generated from washing dishes, bathing and laundry – comprises some 50-80 percent of residential wastewater, and households generate, on average, 2-5 m3 of this resource each week. Estimates suggest that households using greywater stand to gain (on average): a 33 percent reduction in the use of municipal water, a 35 percent reduction in the cost of water, a 20 percent reduction in the costs incurred to pump septic tanks, and increased yields due to the continuous availability of irrigation water.

WLI researchers, in collaboration with other on-going projects and the University of Florida, are exploring the challenges and opportunities for out-scaling household greywater treatment units. Results of the study are forthcoming and are expected to provide valuable insights into the development of appropriate dissemination strategies.