Optimal Irrigation Scheduling for Garlic (Allium sativum L.) in the Central Highland Vertisols Areas of Ethiopia

Abstract

For sustainable utilization of limited available water resources in irrigated agriculture , accurate estimation of crop water requirements and irrigation scheduling is crucial to improve irrigation water management and crop productivity. Therefore , the objective of this activity was to evaluate the responses of Garlic to the irrigation regime (when and how much to irrigate). The field experiment was conducted at the main station of Debre Zeit Agricultural Research Center during 2016, 2017, and 2018. Five treatments for allowable soil moisture depletion levels (ASMDL) of Irrigation at 60%, 80%, 100%, 120%, and 140% were used. Application of irrigation water for Garlic was scheduled when 30% of the total water available in the soil profile was depleted. Treatments' were laid out in RCBD experimental design with three replications for each treatment. From the study, it has been observed that there was a significant difference in marketable yield and water use efficiency (WUE) among treatments. The maximum marketable bulb yield (7.5 t/ha) and WUE were observed from applying irrigation water at 20% more of recommended ASMDL and followed by 40% more of ASMDL (6.7 t/ha) but the lowest (4.68 t/ha) was recorded at 40% less of recommended ASMDL. Reducing the soil moisture depletion level by 40% and 20% from the recommended fraction (0.25) has significantly increased the water use efficiency. Under irrigated Garlic a shorter frequency with a smaller amount improve yield and water productivity than irrigating with wider interval but a larger amount. Therefore, managing the soil moisture content above the allowable depletion level like 60% ASMDL and 80% ASMDL was better than the recommended allowable depletion and the other lower levels. Hence it is recommended that for higher yield and maximum water productivity it is better to irrigate Garlic frequently.