Experimental observations on interaction between a root and droplets in relation to aeroponic agriculture

Abstract: Aeroponics or Soil-less agriculture is a relatively new and recent type of practice, where plants are grown without soil while nutrient-rich water is provided via an atomized spray system to the suspended roots. Spray nozzles are easy-to-use in supplying water (and fertilizers) to (mainly) the roots and root hairs of the desired crop (or plant) for production. We characterize a spray nozzle delivering water vertically above against the gravity by measuring, experimentally, its (a) spray drift, (b) spray height, (c) maximum spray angle, (d) spray width, and (e) droplets sizes. Experiments were carried out at different inlet pressures and a majority of the above mentioned parameters were obtained by processing the images captured using optical (or high speed) camera, sometimes along a plane lighted by a high-power laser source. We also studied the spray (or jet) behaviour at different vertical heights and different horizontal planes using a unique polythene sponge method. We studied the mass flow rate, the absorption rate, and droplet size dynamics (as a function of time and pressure) using this method. The water drop/droplet interaction was also studied in the case of simpler porous and impervious surfaces as well. We believe that this study can be extrapolated to other nozzles (especially sprays) to obtain similar characteristic parameters. This study, hence, is critical in selecting the desired spray system for a given canopy and is also expected to be of some use in controlled agricultural practices such as in greenhouses and apartment rooms.