Drift (crop protection)
Under drift or drift, the proportion of discharged crop protection agent amount is meant, which is not annealed during the application within the treated area.
Possible causes
For aerial drift of pesticides , there are several, mostly technical and meteorological reasons:
- Driving speed : As a rule, driving speeds of 6 to 8 km / h should not be exceeded. Otherwise, the smaller drops in particular will no longer go safely to the ground, but will swirl behind the syringe.
- Spray height : The optimal distance between the nozzle and the target area is mainly determined by the exit angle of the nozzle. Today's nozzles usually have a spray cone of 120 degrees. A distance of around 50 cm to the target surface is recommended for such nozzles, and 75 cm for 80-degree nozzles.
- Temperature , humidity : Permanent temperatures above 25 ° C and relative humidity below 30% lead to considerable losses of funds through drift and are therefore not suitable for the application of pesticides.
- Drop size : The drop size is the most relevant influencing factor. When a liquid is distributed using a nozzle , different droplet sizes are created. The smaller droplets in particular are those with the greatest risk of drift. The smaller the nozzle is chosen and the higher the spray pressure and thus the output per second, the smaller the droplets are usually. Droplets smaller than 200 micrometers in size are particularly at risk.
- Water application rate : With regard to the water application rate, pesticide manufacturers provide information on the optimal water application rate. If this amount is not reached, the proportion of pesticides affected by drift is also higher. In addition, because of the lower application rate, smaller nozzles must be used, which can also increase the drift.
- Wind speed : At wind speeds above 3 m / s, plant protection should be avoided if possible, at wind speeds above 5 m / s treatment is no longer justifiable.
Consequences of the drift
- Air pollution : Pesticides can travel long distances through the air . Animals and humans can be annoyed or damaged by this drift.
- Damage to sensitive neighboring crops can occur. Sugar beet, for example, is regularly damaged or completely destroyed by the active ingredient MCPA if it is used to combat thistle in neighboring grain. In particular, if organically farmed areas are hit, the extent of damage is great if the lot is not recognized as organically produced .
- Soil contamination : A study published in 2019 by the University of Neuchâtel found neonicotinoids in 93% of the organic soils and plants examined in the Swiss plateau . According to the study, this could damage up to 7% of beneficial insects.
- Water pollution : Waters can also be contaminated. In many small streams , strong pesticide loads are measured again and again, which in some cases far exceed the permitted limit values.
- The random distribution leads to overdosing and underdosing over a small area. When applying herbicides , overdosing can damage the crop itself. Resistance from insufficiently affected harmful organisms can be the result of underdosing.
Options for minimizing drift
Drift reduction classes for agriculture
Plant protection nozzles are divided according to drift reduction classes: Depending on the nozzle design, pressure, amount of water applied and driving speed, nozzles with 50%, 75% or 90% drift reduction can be used. Distance requirements to z. B. Waters are partly dependent on the drift reduction classes; the higher the drift reduction, the lower the untreated strip can be. Depending on the nozzle, it can be disadvantageous that the droplet spectrum becomes very coarse and thus the wetting of the target plants suffers. In particular, air injector nozzles sometimes have problems with their biological effectiveness.
Time of application
In the morning and evening hours the temperatures are moderate, and sometimes the wind subsides a little. Modern techniques such as GPS-controlled section control and individual nozzle lighting make treatments in the dark easier. In the population one often hears the thesis that the farmers inject at night because they then distribute the forbidden funds. However, it is exactly the opposite: Especially those farmers spray in the dark who take advantage of the positive effects such as calm during the twilight.
Avoidance of aircraft treatments
Due to the enormous altitude and speed, spray planes are extremely critical.
Web links
- Federal Environment Agency: further information on investigation methods
- Air injector nozzles to reduce drift as well as an overview of applications for field cultivation and area crops
Individual evidence
- ^ DLR Rhineland-Palatinate
- ↑ Application in coarse droplets with injector nozzles (ID). Long-term tests on effectiveness and plant tolerance - Part 1 - Werner Rizzolli, Alex Acler, Laimburg Research Center
- ↑ Good professional practice in plant protection, BML brochure , accessed on January 6, 2014
- ↑ Tina Berg: Pesticides: Danger in the Air. In: observer.ch . March 27, 2019, accessed May 4, 2019 .
- ↑ Pesticides in playgrounds. In: tageszeitung.it . May 21, 2019, accessed May 21, 2019 .
- ↑ 93 percent of the organic fields are contaminated. In: 20min.ch . April 7, 2019, accessed April 25, 2019 .
- ↑ Jorge Casado, Kevin Brigden, David Santillo, Paul Johnston: Screening of pesticides and veterinary drugs in small streams in the European Union by liquid chromatography high resolution mass spectrometry. In: Science of The Total Environment. 670, 2019, p. 1204, doi : 10.1016 / j.scitotenv.2019.03.207 .
- ↑ Andri Bryner: Too many pesticides in small streams. In: eawag.ch . April 2, 2019, accessed May 4, 2019 .
- ↑ LWK NRW drift reduction classes .
- ↑ Page no longer available , search in web archives: Lanuv NRW drop spectrum of different nozzles (table 16) .
- ↑ Page no longer available , search in web archives: Hardi GmbH, graphics on page 2 and page 5 on the biological effectiveness of different types of nozzles .
- ↑ JKI, page 56 ( Memento from March 4, 2016 in the Internet Archive )