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Dr. Diego Martin Oliva diegomartinoliva@gmail.com AgrĂ´nomo
Effective Low Applications During a period prior to the fungicide applications in the Republic of Argentina, a group of application companies I usually work with entrusted me with the task of analyzing the minimum liters per hectare can be applied without losing application efficiency? We know the economic result of an aerial application is directly related to the swath, the ferry distance and the liters per hectare applied. It is very interesting to analyze in terms of application efficiency what is the minimum limit with which you can work in low volumes using oil as a carrier. In the beginning of the analysis, it cannot be ignored that the configuration and position of the spray boom is decisive for how many droplets will reach the target. This can be seen in the adjacent graphic. if the vortexes of the wings are loaded, droplets rise and evaporate or drift off target.
In earlier years, this vortex effect was intentionally sought, often due to the vapor phase of some chemicals. Now, we know that if droplets enter the vortexes, most are lost going off target with a very noticeable effect; less droplets find their way to the target with these low volume applications. In the same way, we must also consider what type of boom hanger we are using. Depending on the relative position of the hanger, it will have a drag effect that can be seen in this photo.
A 16 | agairupdate.com
All these aerodynamic effects achieved from an adequate configuration / calibration of the spray equipment are absolutely critical in reducing the flow of application since the coverage can be seriously affected. If we assume that structurally the spraying equipment is in perfect condition and we start analyzing in theoretical terms how many drops are produced according to their size and the liters per hectare, we can arrive at an initial approximation of what is the lower limit without losing efficiency. For this we will apply the volumetric formula:
For example, if we apply five liters of total product per hectare (0.5 gal/ac), we have a droplet spectrum that will equate to 68% of the droplets produced will be 100 microns. We know the theoretical result corresponds to 95 droplets / cm2 should reach the target. So, why do a lot less droplets arrive? How much efficiency are we losing due to small droplets of low average volumetric diameter for applications with an oil carrier? Is it possible to achieve good results with low application volumes? The answer will be directly related to two analytical variables. In theory, the production of drops and their orientation are assured considering the parameters described above. Atmospheric conditions will limit the ➤
