Post on bare soil spraying, by Hans Christian Juel from danfoil

Post on bare soil spraying, by Hans Christian Juel from danfoil.

When one talks about bare soil spraying and Danfoil, there are some who suspect the Danfoil sprayer of creating more drift than the ordinary spraying technique. They refer to a few spraying insistences, which sadly are the only memories they associate with Danfoil. But with the right settings for the sprayer, Danfoil's spray technique is the one that has the lowest drift compared to the conventional spray technique – at approximately the same level as sprayers with assisted air. This has been proven by several drift tests performed by the Danish Institute of Agricultural Sciences and the German JKI. Even more important, practical experience from danfoil users has shown that it is possible to spray on bare soil with 7-8 sec./M, with good results and without drift.

What is the proper settings regarding air pressure, boom height, water volume and driving speed?

It is a known fact that it is the air pressure that determines the size of the drops and when one is talking about bare soil spraying one should use a "heavy" drop, because it is more difficult for the wind to move, which will help preventing drift. The Danfoil system will almost always generate a little turbulence, but this is an advantage because some of the drops then will get under soil clods and stones, and thereby prevents the onset of germination. Therefore, our recommendation is an air pressure between 10-13 cm/WS.

The boom height is very important. Each time the boom height is increased by 10 cm, the risk of drift doubles. With Danfoil eurofoil, one can spray with the lowest boom height on the market, down to 40 cm from the surface of the ground, and one can easily spray under hostile conditions.

The amount of water has little impact on the size of the drops and the effect of these, but when one is down to 10cm/WS there is too few drops, and one needs to increase the water volume to minimum 40-50 l/ha., otherwise one does not get a sufficient number of drops to cover the surface.

A rule of thumb is: less air more water, but maximum 70 L/ha. One should bear in mind that when one increases the volume of water, to e.g. 70 l/ha, one should slow down to a driving speed of maximum 6 km/h, else a consistent spectrum of drops and optimal deposit cannot be achieved. If the weather is hot and dry, the experience is that it is beneficial to increase the flow of water a bit. Alternatively, one can spray when there is dew. It will always be the moisture of the soil that determines whether the effect is good. And remember: 1mm. rain is equivalent to 10,000 L/ha.

Driving speed also is of great importance to drift. Ever time the speed doubles, the risk of drift triples. If one is spraying in extreme conditions, it is recommended that the driving speed is 5-6 km/h, especially in the outlaying round. When driving in direct headwind or tailwind, the driving speed can be regulated according to the wind direction. If conditions get favorable, most will increase driving speed, which will lead to increased capacity.

Recommended setting:

The recommendation are as followed:

• Air pressure: 10-13 cm/WS,
• Boom height: 40 cm, 
• Amount of water: 40-50 L/ha,
• Driving speed: 5-6 km/h.

Please note that if one is driving with 10 cm/Ws, then one needs drive with 50 l/ha. If one is driving with 13 cm/Ws, then water consumption advantageously can be reduced to 40 l/ha.

If one follows this advice one can always spray bare soil up to 8 sec/m, with good spraying effect and without drift.