Most spray booms are being carried too high, compromising efficacy and leading to excessive drift.

Article taken from CPM Supplement ""Talking"" series.


Most spray booms are being carried too high, compromising efficacy and leading to excessive drift.

Booms are getting wider, without enough thought being given to stability, while forward speeds are also increasing to maximise work rates, making the boom less stable.
""The key thing about application is the closer the nozzle is to the target, while still achieving the correct spray pattern, the better the performance is going to be," says Agrovista technical manager Chris Martin.

""The biggest problem these days is that the opposite is happening. Not only are many booms unable to spray below 60-70cm, they are actually being carried higher.""

As boom height increases, the spray pattern suffers and drift increases rapidly — this can be as much as eight times higher at a boom height of 100cm compared with 50cm, he explains.""If you can reduce your boom height below 50cm, that's a real step in the right direction.""
BoomControl Pro allows this, thanks to its 25cm nozzle spacing, which allows nozzles to be carried at 25-50cm while maintaining the correct spray overlap.
""I really like this arrangement. To achieve optimum coverage you want higher water volumes whilst retaining a finer spray quality, especially important on difficult targets such as small black-grass.
""Using 25cm spacing rather than 50cm means you can double the water volume being applied across the boom without losing spray quality. Because the boom is so close to the target you can use a 02 or 025 nozzle without drift becoming a major problem.

""You have 64 times as many droplets using a fine nozzle with a droplet diameter of 100 microns than a coarse one with droplet diameter of 400 microns at the same water volume. This achieves much more even coverage as the spray almost paints the target rather than relying on big droplets spreading out.""

This can make a huge difference. For example,Agrovista trials over many years have consistently shown that up to 50% better black-grass control can be achieved from the same pre-emergence products through using better application.

Forward speed can also be increased when nozzles are close to the target without sacrificing performance, Mr Martin adds. Using a conventional boom carried at 60-70 cm or more at normal pressures and volumes, increased forward speed significantly increases turbulence and drift starts to become a significant problem. But at a boom height of 25-40 cm it is much less noticeable, says Mr Martin.

Mr Martin believes the technology could give a massive boost to spraying efficacy. Compared with the cost of the chemistry being applied over the life of the sprayer, it represents a relatively modest investment, he adds.