Air sprayer with potential to reduce active ingredient usage

A innovative air sprayer with the potential to reduce the amount of water used to desiccate potato crops prior to harvest without compromising yield and quality is becoming increasingly popular in Denmark, Sweden and Germany. Tillage Technology’s Heather Briggs speaks to Jesper Madsen, managing director at one of Europe’s leading innovators in this field, the Danish company Danfoil.

The air sprayer, which uses air as a medium to create fine droplets, unlike conventional hydraulic sprayers and airassisted sprayers, is proving a hit with potato growers, according to Mr Madsen. This is partly because the innovative technology in a Danfoil field sprayer reduces water consumption, he explains.

On average, the sprayers use a water volume of just 30-50 l/ha, rather than the more usual 200 -500l/h), thereby increasing the amount of land sprayed per tankful. This creates savings in both labour and tractor fuel and even further savings because there is no need to change the atomisers as required by traditional sprayers, claims Mr Madsen.

Variable droplet-size makes it possible for the user to adjust the size of the droplets to the specific spray job and ensure optimal coverage and low drift. The droplet size is controlled solely by the air pressure; the higher the pressure, the smaller the droplets. Moreover, he adds, the amount of active ingredient (ai) needed is also reduced when desiccating potatoes, which can benefit the environment.

This was corroborated by a recent survey carried out by Danfoil, which showed 82 per cent of the potato farmers in a trial reduced the concentration of pesticide compared to the recommended dosage stated on the label of the chemicals.

Mr Madsen says: “On average, these potato farmers reduced recommended dosage on the label by between 30 and 40 per cent.

“Of these farmers, 89 per cent who have reduced their chemical consumption, have not seen any negative yield effects.”

Nevertheless, he points out, the study shows a huge variation in the degree to which the respondents have decreased their use of pesticides during potato desiccation. This is mainly because different soils, topography, rotations, micro-climates and other variables mean that no two farms are the same.

The air sprayer can also be used with plant protection products. However, when used this way, although some respondents reported reductions in the amount of insecticides, fungicides and herbicides applied, in general the reduction in pesticide consumption has not been as significant as for desiccating, he cautioned “We need further information to help farmers create best practice for using a Danfoil field sprayer, as research shows that it is possible to reduce chemical consumption by 50-75 per cent when spraying plant protection products.

“At the moment, it is the individual farmer who decides the dosage based on personal experience. This illustrates that as yet there is work to be done to create and refine guidelines on the amount of active that should be used with Danfoil field sprayers.”

He goes on to say that when assessing any potential impacts of pesticide reduction on quality and yield, it is important to take build information because of year-on-year variations in the weather which can also result in deviations.

Such differences mean that spray operators need to take time to get the best out of their spraying machinery.

“It is important to remember that it takes experience and training to operate a Danfoil field sprayer, and it is not possible to learn all the nuances to ensure optimal performance within a single season.”

He emphasises that care of the environment is also of great importance to Danfoil. For example, in 2017, Danfoil received a 90 per cent drift reduction approval from the recognized German Julius Kuehn institute (JKI). 

“We have developed a way to reducing consumption of water and pesticides, and this has a double benefit, as not only does the farmer benefit, but we have paved the way for a more environmentally friendly farming. This is a win : win situation.”

How the sprayer works
An atomiser, using air as the medium to create fine droplets, is quite different to air assisted sprayers and conventional hydraulic systems, points out Mr Madsen.

This is because although the sprayer has a tank, pump and pipes, it has no nozzles; just one atomiser which distributes the liquid, he explains. Air pressure is used to pass air past an atomising plate holding the liquid, which atomises the liquid and droplets form on the bottom of the plate. In dense crops, such as potatoes once the canopies have grown together, by creating turbulence around the plant the liquid is distributed at the top and bottom of the crop, in addition to spraying both the upper and underside of leaves, he explains. In open fields droplets are distributed by horizontal air movement.

“The absolute key-word behind our technology is simplicity,” continues Mr Madsen. “The structure is simple, easy to adjust and use for different spray tasks – thanks to a user- friendly computer system.

“Cleaning, adjustment, and maintenance are reduced to a minimum.

“Moreover, it is really easy to clean the sprayer because the water is heated by the sprayers’ hydraulic system and therefore allows you to clean with hot water, while you are in the field.”