A low-cost integrated desalination and irrigation technique tested on dual-purpose sorghum in Turkana County, Kenya

In arid and semi-arid lands, water salinity often restricts plant growth, degrades soils, and even causes irrigation systems to fail, especially in hot climates. Worldwide, it is a “major cause” of the irrigation-induced salinization that had already affected 76 million ha of soil in 1991. Our novel and inexpensive irrigation technique addresses these issues, thus potentially improving the food security of affected farmers and pastoralists who often are amongst the world’s poorest. Saline or brackish water is dispensed inside plastic bottles that are modified so as to feed only vapour to the soil, where roots and moisture-retaining materials can capture it. We tested this method in the field in Turkana County (Kenya) with Dual-Purpose Sorghum. Five treatments in five replicates were applied with different moisture-retaining material: biochar; organic mulch; plastic sheeting; Super Absorbent Polymer); and none (Control). Effectiveness of the treatment was appraised by comparing the average heights of plants. At 64 cm after 30 days, the Super Absorbent Polymer treatment performed best (34% better than the control, p=0.05), followed by organic mulch (18% better than the control, p=0.05). Super Absorbent Polymer and organic mulch also retained the most moisture in the soil (37 and 32% better than the control, respectively; p=0.05). Key words: Irrigation, pitcher irrigation, condensation irrigation, superabsorbent polymer, mulch, salinity, brackish water, saline water, soil salinization.