Submitted to: Transactions of the ASAE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 9, 1998
Publication Date: N/A
Interpretive Summary: Inline injection of pesticides is a sprayer technology that offers many advantages over traditional, single-tank sprayer systems. Left-over tank mix, application rate errors due to driving speed, and safety hazards from pouring pesticides are some of the problems inherent to single tank sprayers controlled with injection systems. Spray application rate can be varied while spraying which allows implementation of precision farming methods. However, injecting pesticides into a supply line results in a lag time from the onset of a new chemical rate until that rate reaches all nozzles. We used a unique, computer controlled system to measure lag time for a range of nozzles per boom section, two nozzle supply line sizes and for simulated pesticides with a range of viscosities. These results are the first to show lag time did not increase greatly with an increase in the number of nozzles in a boom section supplied by one injection point, that viscosity of the injected material has little affect on lag time, and to develop an equation, based on experimental results, that can be used to calculate lag time at the end of the spray boom based on boom diameter and number of active nozzles. Manufacturers will be able to predict lag time for planned sprayers, during the design phase, using nozzle-number for each boom section and boom supply-line size. These results should also help growers set up field sprayers for most effective spraying results.
Technical Abstract: Lag times were measured for an inline injection sprayer system. Lag time was the time period between when an injected pesticide rate changed and when the new pesticide rate reached nozzles on the boom. Lag time factors investigated were: number of active nozzles, boom size, travel speed changes, and pesticide viscosity. Three water-soluble and one non-water- soluble simulated pesticide liquids (water, Prime Oil, Prime Oil II and Silicon Oil) with viscosities that ranged from 0.9 to 97.7 mPa s were used. An equation was developed to predict the lag time at the nozzles at the end of the spray boom. Lag time was greatly reduced by reducing the boom diameter, but was not reduced substantially by decreasing the number of active nozzles on the boom. Lag times were not affected by viscosity of the simulated pesticide.