For each PPP a minimum buffer zone is fixed at its authorisation. This buffer zone depends on the toxicity with regard to water organisms. This buffer zone can be reduced, provided the following conditions are fulfilled:
- Within a zone of 20 m the farmer can drive, depending on the nozzle equipment and other requirements, at a speed of max 5 km/h
- a max distance to crop of 50 cm has to be kept
- With the use of drift reducing nozzles and depending on pressure, the buffer zone can be reduced.
- If the volume of applied PPP is reduced by 50%, the buffer zone can be reduced to the subsequent legal buffer zone.
- in case the concerned water body is a flow water, the buffer zone can in principle be reduced by 25%. (must be notified in the register and on the label!!)
- vegetated buffer strip along the water body
If along the water body there is a vegetated zone with vegetation of at least 1 m height and which exceeds the the nozzle height by 1 m, the regular buffer zone can be reduced by 25%, as a general rule. (must be noted in the register and the label).
- with band and under-leaf applications a minimum distance of 1 m is to be observed along surface waters
- the minimum distance of 1 m must in no way be reduced.
Spray drift reducing technology can be used to reduce buffer zone width. Austria also provides for the possibility to use SDRN in regulatory risk assessment. SDRT represent a combination of sprayers, operating conditions and approved nozzle type. Reduction classes are 50, 75, 90% in arable crops and 50, 75, 90 and 95 % in orchards.
A practical example:
Product Artist (Regular buffer zones in m: 20/10/5/3) us to be applied on a soy field. PPP application equipment: nozzles Agrotop AirMix 110-04. This nozzle is to be used with a pressure of 2 bar, drift reduction potential : 50%. The field is next to a brook with bank vegetation.
Herbicide use: Artist -> 20 m buffer zone
Nozzle with SDR 50% -> next buffer zone: 10m
Flowing water -> -2,5 m (-25% of 10m)
Bank vegetation -> -2,5 m (-25% of 10 m)
new reduced buffer zone: 5m
Hence, over a width of 20m, calculated from the new buffer zone (in the present case: 5m) the following requirements must be observed: 2 bar pressure, max 5km/h speed and boom height of 50cm (from soil). From 25 m distance to upper water body edge the optimal pressure, boom height and speed can be applied again.
Attention ! Partly, required buffer zones depend on application volume, area of use, etc.. With some products there are application restrictions with regard to surfaces susceptible to runoff. There are additional measure to reduce risk from water contamination, such as the use of mulch, vegetation, rough seedbeds, green strips or crosswise dikes. Minimum safety distances may be required, or the set up of grassed strips. In any way, operators are urged to check labels for minimum safety distances !