Determination of Optimum Irrigation Scheduling for Onion (Allium Cepa L.) at Bena Tsemay District, Southern Ethiopia

Abstract

The effective use of irrigation methods is crucial for increasing crop productivity and promoting the
sustainable use of agricultural land. Therefore, increasing agricultural water productivity is one of the most important
ways to counteract future water scarcity. A field experiment was conducted to determine the optimal irrigation regime
for onion cultivation in Bena Tsemay district for two consecutive years. The experiment was laid out in a randomized
complete block design with five irrigation treatments and four replications. The treatments included five levels of
irrigation regimes: 60%, 80%, 100%, 120% and 140% available soil moisture depletion levels. The results showed that
irrigation regimes had a significant effect on plant height, bulb diameter, marketable yield and total yield, with a p-
value of less than 0.05. The highest marketable yield (30.72 kg/ha) was observed at 100%ASMDL, followed by (30.49
kg/ha) at 80%ASMDL. However, irrigation at 140%ASMDL resulted in the lowest yields of both marketable and total
onion. The two-year combined analysis revealed that the highest (6.5 kg/m3) water productivity was recoreded at 100%
ASMDL, followed by (6.45 kg/m3) at 80% ASMDL. In contrast, the lowest water productivity (3.21 kg/m3) was
recorded at 140% ASMDL. Therefore, based on the results of the current trial, it is recommended that the use of 80%
ASMDL for a furrow irrigation system, and in similar agro ecology is a crucial option to increase the yield and water
productivity of onion