Design and performance evaluation of self-propelled intra-canopy boom spraying system

Abstract

A self-propelled intra-canopy boom spraying system was designed for spraying chemicals in small height row crops. The performance of the spraying system was evaluated both under laboratory and field conditions to assess the efficacy and minimize the loss of spray liquid. Flat fan and hollow cone nozzles were tested to determine the boom volumetric distribution, swath and spray angle at different combinations of pressure and height. The flat fan nozzle gave better volumetric distribution at 2.5 kgf.cm-2, while the hollow cone nozzle gave at 2.0 kgf.cm-2 pressure corresponding to 300 mm nozzle height. The spraying system was tested on soybean crop at forwarding speeds of 1.5, 2.0 and 2.5 km.h-1. With an increase in forwarding speed, the mean percentage of coverage decreased significantly (30.30 - 15.37 % for top and 20.01- 4.12 % for bottom part of the leaves), and the mean droplet density varied significantly (277.35 - 243.40 no.cm-2 for top and 262.87 - 78.44 no.cm-2 for the bottom part of the leaves) at 5 % level of significance. A good percentage of leaf area coverage (30.30 % and 20.01 % for top and bottom of the plant) was obtained at low forward speed (1.5 km.h-1) while compromising more spray volume and less field capacity as compared to higher forward travel speeds. The effect of forwarding travel speed, position of tags and nozzle types were significant (p<0.05) for mean droplet size, number median diameter, percentage coverage of leaf area and droplet density. The field capacity of the spraying system ranged between 0.22 and 0.36 ha.h-1 with an increase in forward travel speed from 1.50 km.h-1 to 2.50 km.h-1 at an average swath of 1.8 m.