Dynamic changes in bubble profile due to surfactant and tape orientation of emitters in drip tape during aerated water irrigation

Use of aerated water for drip irrigation using a pressure differential Venturi has been reported to produce positive response on crop yield and water use efficiency. We present two options for increasing the distance from the source of irrigation an air/water mixed phase travels. We discuss observed results for a row length of 500 m of drip tape. The first option relates to the orientation of drip tape emitters to the ground plane. In the up orientation the emitters are on the top of the drip tape and in the down position the emitters are along the bottom of the drip tape. We found higher air void fraction with the emitters down, compared to the standard placement with the emitters up. We also discuss observations of field trials for this treatment. The second option explored two concentrations (2 ppm and 4 ppm) of BS1000™ surfactant in irrigation water in the drip tape. Bubble size decreased, whereas air void fraction increased along the length of drip tape, with increased concentration of surfactant, in both up and down emitter positions in the drip irrigation tape. The best result was using non-ionic surfactant at 4 ppm with the emitter facing down where the bubble distribution and the availability of micro-bubbles over the 500 m irrigation was greatest. This knowledge will be of benefit in drip and sub-surface drip irrigated agriculture.