Irrigation & Drainage Systems Engineering

Integrated Effect of Partial Root Drying and Mulch on Onion Yield and Water Productivity in Ethiopia\'s Central Rift Valley

Abstract

Ketema Tezera*, Gobena Dirirsa, Aynalem Gurms, Tigist Worku, Abera Tesfaye, Gebeyehu Ashemi and Tatek Wondimu

Irrigation is a vital practice in the Central Rift Valley of Ethiopia. However, water scarcity is the major limiting factor of agricultural production and productivity in the area. The field experiment was conducted on clay loam soil at the experimental field of Melkassa Agricultural Research Centre to evaluate the effect of furrow irrigation techniques and mulch types on onion yield and water productivity. The experiment was arranged in a split-plot design with three replications. The treatments include three furrow irrigation techniques (conventional, fixed, and alternate furrow irrigation) as main plot and mulch types (plastic and straw) and a control treatment of no mulch as sub-plot. The highest significant average bulb yield of 35.9 t/ha was obtained at the conventional furrow technique and the lowest average bulb yield of 24.6 t/ha was recorded at the fixed furrow irrigation technique. The bulb yield reductions with partial root drying that resulted in 50% water saving at both alternate and fixed furrow irrigation from conventional furrow irrigation were about 25, and 32%, respectively. The highest significant average bulb yield of 32.4 t/ha was obtained at the plastic mulch type and the lowest average bulb yield of 25.4 t/ha was recorded at no mulch treatment. The bulb yield increased with the use of mulch type from bare to straw and plastic mulch was 15 and 28%, respectively. Irrigating using conventional furrow technique using plastic mulch was found to be the most effective. It produced a significantly high bulb yield of 38.6 t/ha as against the fixed furrow method at no mulch type, which resulted in a bulb yield of 21.5 t/ha. Water productivity was higher for alternative furrow and lower water productivity was obtained from conventional furrow methods. Mulch types had a significant (p<0.05) influence on water productivity. Therefore, under a limited water supply area it can be concluded that more water-saving and associated increase in water productivity with alternate furrow irrigation and plastic mulch can solve the problem of water shortage. The study suggested that producing onion with plastic mulch resulted in higher product and water productivity.