EFFECT OF DRIP LATERAL SPACING AND MULCHING ON YIELD, IRRIGATION WATER USE EFFICIENCY AND NET RETURN OF ONION (Allium cepa L.) AT AMBO, WESTERN SHOA, ETHIOPIA

Abstract

Despite the fact that irrigation water and cost of production are the most limiting factor for vegetable production in areas where rainfall is unevenly distributed temporary and spatially, limited information has reported on means of minimizing production cost and improving yield and water productivity using modern irrigation system and water conservation methods. Hence, the field experiment was conducted at Ambo during the dry season of 2017/2018 to investigate effects of drip lateral spacing and mulching on yield, water use efficiency and net return of onion production. In this research 8 treatments with three replications were randomized in complete block design to conduct the experiment. Two levels of drip lateral spacing (drip laterals in every plant rows and drip laterals between two rows) and four levels of mulch (no mulch, wheat straw mulch, white and black plastic mulches) were used to evaluate their effect on onion yield, water use efficiency and net return.100% ETc of irrigation water was applied throughout growing season for all plots. Yield and irrigation water data were subjected to ANOVA using SAS software with significance level p ≤ 0.05. LSD test was applied for statistically significant parameters to compare means among the treatments. The result showed that both onion yield and water use efficiency was affected by main effects of drip lateral spacing and mulching but not affected by their interaction effect. The maximum bulb yield (34990 kg ha-1) of onion was recorded from onion grown under drip lateral in every row. In case of mulching, the highest mean bulb yield of (35117 kg ha-1) was obtained from white plastic mulch. The highest water use efficiency of 1.14 kg lit-1 was recorded from onion grown under drip lateral spacing in every row and 1.15kg lit-1 was from white plastic mulch. Even though white plastic mulch scores significantly higher yield and water use efficiency, based on the partial budget analysis highest net return of 246,410ETB ha-1 and 284,616ETB ha-1 were obtained from drip laterals in every rows and no mulch, respectively. This suggests that drip laterals in every rows and no mulching is economically feasible for drip irrigated onion production at Ambo.