FOIL DROP GENERATOR FOR FOLIAR CHEMIGATION: FIELD EVALUATION

Abstract

Chemigation field experiments were conducted with a new drop generator for oil-based foliar chemicals. Thedrop generator was adjusted to generate two drop-size distributions with dmax of 980 m and 98 m. Soybean oilconcentration in sprinkler sprays was measured along the 379-m-long center pivot irrigation pipeline; uniformitycoefficients along the center pivot pipeline were 73% and 98%, respectively. An experiment with a conventional straighttube injector was also conducted, and calculated dmax was 1850 m; oil discharge uniformity coefficient along thepipeline was 61%. The calculated drop-size distributions for the three experiments were input into a dispersed phasepipeline transport model; the model calculates oil discharge concentration versus distance along the pipeline. The rootmean square deviation error between experimental and simulated concentration curves were 40%, 28%, and 3% for thestraight tube, 980 m, and 98 m experiments, respectively. The models were used to develop graphs for dischargeconcentration uniformity as a function of dmax and relative density of oil and water in the pipeline. The model simulationsand experiments showed that the drop generator and two-phase transport model provide the ability to control oildischarge concentration uniformity along a center pivot pipeline.