Evaluation of low-head drip systems for vegetable farming in Bangladesh
Bangladesh is in the phase of introducing drip irrigation (DI) system in the country. Several types of drip emitters are now becoming available in the market although their performance indices are yet to be matched for local farming practices. This study reports the results of a series of experiments carried out to quantify the hydraulic performances indices of two different types of emitters available in Bangladeshi marketplace. One of the emitters, E1 was designed and manufactured locally, while the other, E2 was imported and highly priced. Followed by the hydraulic experiment, these emitters were also employed in comparative field experiments for tomato and brinjal production at two separate locations in the country. Irrigation schedules were designed based on the local evapotranspiration regime. During the study, both the emitter types exhibited non pressure compensating features as their flow rate increased with pressure. Interestingly, both types of emitters gave a persistent trend of flow rate along the laterals. Standard uniformity indices for DI systems were also calculated, and the DI systems were categorized (good to excellent) based on the established guidelines for microirrigation. Very good performance indices were obtained at 3 m head for emitter E1, and at 2.5 m head for emitter E2. The results of the field experiments also showed that yield, water saving and water productivity of drip irrigated tomato was increased by 12%, 49.48% and 49% respectively when compared with furrow irrigation that is considered as a farmer practice. Similar results were also obtained for brinjal fields irrigated under DI systems. These experiments showed promising comparative benefits of drip technology for vegetable cultivation in water scarce coastal areas of Bangladesh.