Performance of a ring-shaped emitter for subsurface irrigation in bell pepper (Capsicum annum L.) cultivation

Abstract

A low-cost subsurface irrigation system with ring-shaped emitters has been applied and considered as a way to improve water irrigation efficiency in a region where farming is performed on a small scale, especially in rural areas of Indonesia. To build a ring-shaped emitter, a rubber water hose was bent into a ring shape with a diameter of about 20 cm, and a given number of 5-mm holes were drilled into it. The ring-shaped hose was then covered fully with a permeable textile so that irrigation water can be distributed in all directions around the emitter. Our previous study showed that, depending upon the soil type, the number of holes can be reduced from 5, which was originally used, to 2. We also proposed an emitter that was covered partially by the permeable textile to simplify maintenance. The study showed that the partially covered emitters performed similarly to a fully covered one. This study aims to investigate the performance of the newly designed emitter, with two drilled holes, in bell pepper cultivation. Cultivation experiments were carried out in a greenhouse during the summer of 2017. In the experiment, a bell pepper nursery was planted in a plant pot in which the ring-shaped emitter was buried at a depth of 15 cm. In addition to the newly designed emitter with two holes that was partially covered by the permeable textile, the original fully covered emitter with five holes was used in this experiment for comparison. Water was then supplied from a Mariotte tank connected to the buried emitter by maintaining a water pressure head of 1 cm at the inlet of the emitter for 2 h during cultivation. Plant heights, biomasses and yields were measured to determine water-use efficiency. As a result, while the irrigation was more efficient with the modified emitter in terms of enhancing root zone water distribution and water use efficiently (96.0% with the new emitter compared to 75.2% with the original emitter), plant growths were not significantly different. This study suggested that subsurface water application using a modified ring-shaped emitter will be able to maintain soil water content (SWC) in the root zone properly without causing water stress for plants.