Use of simulations to study herbicide site specific spraying
Résumé
Site-specific weed management is one of the potential ways to reduce the chemical amount required to control crop weeds. Sources of optimization were investigated with spray width from an individual nozzle or a boom section width and spray deposition patterns were applied to different spatial coverage rates of weeds. The objective was to quantify herbicide saving possibilities as well as potential under-application areas. Simulations were performed with a collection of virtual weed infestation maps and an actual infestation map derived from aerial images. Results issued from the computation were expressed in terms of three indicators: i) the ratio between herbicide amount in the case of a site-specific application and the amount deposited in the case of an application on the full field surface area, ii) the proportion of weed coverage on which the application rate is higher than 85% of the rated dosage, iii) the proportion of the weed surface on which the deposited application rate is lower than 50% of the rated dosage. The interest in reducing the section width depends on weed spatial distribution and aggregation degree. Moreover, in the case of uniformly dispersed small patches and the use of narrow sections (1 to 4 nozzles) equipped with triangular spray pattern nozzles, attention should be put on the increase of under-dosing areas.