Farm-scale water productivity for tomato with mulched drip irrigation

Abstract

Water productivity relates to the amount of yield per unit of water used. Water productivity is not reported for most crops in Iraq and the Kurdistan Region of Iraq (KRI) where water scarcity recently forces farmers to shift from traditional farming methods including surface irrigation on bare soil to modern practices including drip irrigation and mulch. This study is the first attempt in Iraq and KRI to calculate and report water productivity for tomato ( Solanum lycopersicum ) under drip irrigation with plastic mulch at the farm scale. Data of yield production, the number of irrigation, irrigation duration, and data of cost and benefit of production were collected in 2021 from 32 farmers who produced tomato from an area of 95 ha. The yield, water use, and water productivity were then calculated. The mean values were 82.7 ton ha -1 , 31,083 m 3 ha -1 , and 2.8 kg m -3 for yield, water use, and water productivity, respectively. Hence, to produce 1 kilogram of tomato, 350 liter of water was applied. Farmers irrigate the farms each time 2-3 times longer than in previous years. Thus, this water productivity value is lower than many values reported in the literature for drip irrigation and surface irrigation even, likely due to lower rainfall amount in 2020-21 compared to the previous season. Cost-benefit analysis shows that 21% of production benefits are water use, 14% is production cost and the remaining 65% is a net benefit. Although a substantial amount of water is used, tomato production is a profitable emerging business in the area. The recent shift from surface irrigation on bare soil to drip irrigation and mulch is a successful strategy in adaptation to current water scarcity in the region.