Pesticides are used by farmers to provide crop protection against various pests and diseases. If managed incorrectly however, contamination of watercourses by pesticides can lead to adverse impacts on aquatic life and have implications for drinking water supplies. To reduce the potential impact, farmers can take proactive steps to water protection and management on their land.
Biobeds or biofilters provide a biological treatment system for dilute pesticides and research has shown they are an effective way to treat drips and spills from sprayer handling areas as well as sprayer washdown.
Both systems use a biomix composed of one part compost, two parts straw and one part soil and can be used to treat up to 15,000 litres of pesticide washings within a 12-month period (Environment Agency waste exemption and permit requirements will need to be checked before implementing either system).
Grant aid funding for both systems is available through Countryside Stewardship.
The more expensive of the two systems, biobeds are impermeably lined pits, filled with biomix and covered with turf. Waste liquid from the pesticide handling area is trickle irrigated onto the surface of the biobed. The liquid then filters through the biomix resulting in up to 100,000 fold reductions in pesticide levels. Treated water leaving the biobed is either stored in a separate container or directly irrigated onto a vegetated area.
Better suited to smaller sites, biofilters consists of three intermediate bulk containers (IBC) ideally located undercover to exclude rainwater. Each container is filled with the same biomix as biobeds overlaying mesh and pea gravel. Waste liquid is pumped up to the highest of the three containers, stacked within a frame and located within a bunded area, and gravity flow allows the liquid to filter through. The treated water can again be stored in a container or directly irrigated onto a vegetated area. Some recirculation of treated water may be necessary with biofilters to keep the biomix wet.
Water protection methods such as biobeds or biofilters help farmers to avoid breaching water regulations through pollution of watercourses and provide a method to effectively manage spills and washings from pesticide handling activities.
Treated water can also be put back into agricultural use such as washing down sprayer exteriors or irrigation purposes.
Biobeds and filters degrade pesticide residues from pesticide handling operations. This reduces the risk of pollution arising from pesticide residues entering watercourses and helps to protect aquatic life.