AN EXPERIMENTAL SPRAYER FOR THE SPATIALLY SELECTIVE APPLICATION OF HERBICIDES

An experimental agricultural spraying machine for investigating the ef fects of applying spatially variable herbicide doses is described. Des ign features of the machine which affect spatial resolution and steady -state accuracy of herbicide dose are examined. Experiments have shown that the steady-state dose can be controlled to within +/-5% of the s et value over the system range. When using the injection metering syst ems to control dose, the sprayer will typically travel 11m before the effect of a change in set dose rate is seen at the nozzles. Using sole noid valves, four levels of dose rate can be applied within 0 . 5 m of a command. The finite lime taken for injection metering systems to re spond to changes in water flow rate as sections of the boom are switch ed on and off, can cause dynamic errors in applied dose.