Background Research Summary Ver1.4 Farm Biobed Systems - to limit point source pollution from pesticide handling and washdown areas. Background Research Summary Developed for the Crop Protection Association and Agricultural Industries Confederation by ADAS. The assistance of the Environment Agency, SEPA & the Farming Unions is also acknowledged. This is part of the voluntary initiative to minimise the environmental impact of pesticides

Pesticides in water: sources of contamination Diffuse Point Source Non-crop use drift tank filling roads drainflow waste disposal pavements surface flow washings railways interflow/base faulty equipment other hard seepage surfaces leaching spillages amenity areas

Pesticide handling areas account for 40-70% of pesticide contamination of water Swedish research 1000 biobeds in use a significant reduction in pesticides found in surface water Systems include a biobed directly under the sprayer, which stands on a grid or wheel support system. UK studies suggested inclusion of a ‘drive over or direct’ system and use of containment around a concrete surface of a sprayer filling area directing discharge to a biobed. 3 systems set up in Lincolnshire at commercial scale with full monitoring for 2 seasons.

Pesticide Handling? Loading Filling Mixing Moving Washdown Interior Exterior Small Quantities High Concentration Part of the Application Process Large Quantities Lower Concentration Disposal Operation unless “applied” in the field

Pesticide Handling Area: Offset or Drive Over Offset - the handling area separate from the biobed area Drive Over - the handling area directly over the biobed area

What is a biobed used in the study? A hole in the ground with an impermeable liner and coupled drain-The liner was necessary for controlling discharge and sampling outflow. 2 systems filled with composted mix 50% by volume straw, 25 % soil, 25% peat free compost (Biomix) and turfed over 1 system filled with friable sandy loam soil, not compacted with grass turf over

Biobeds challenged by commercial use plus pesticide contamination artificially TWICE in one season The artificial treatments simulated maximum contamination losses from 16 tank mixes on one day with worse case practice on each load. This contamination would have needed a water volume equivalent to 60 Olympic size swimming pools to meet 0.1g/L 6 pesticides were used as artificial contaminantsas in previous experimental studies. These were sprayed or ‘spilt’ onto each system in addition to inadvertent chemical addition from commercial use 2 artificial applications June and September 2002, 55 days monitoring afterwards

Pesticides used as contaminants Source types, volumes and concentrations applied

Typical concentrations (g/L) after artificial application to concrete pad to biobed (Similar results were found on the soil based system)

Typical concentrations (g/L) after application to Drive-over Biobed Note: No surface figures quoted as the grid did not retain any liquids. Types,volumes and concentrations applied as for other 2 systems

Max. concentrations measured (g/L) Key Points - Over the two 3-month monitoring periods: Input concentrations typically reduced by 10,000-100,000 fold >1100 individual pesticide determinations from leachate samples 87% of leachate determinations had concentration <0.5g/L (<LOQ)

Operational Aspects Water Storage - Flow Management & Biobed Moisture Drip Irrigation to Biobed and Disposal Area Annual Biomix Top-up Lining to Biobeds Winterisation Long Term Biomix Disposal - Residues

Water management - Storage, Distribution and Biobed Moisture Offset systems Receive rainfall from sprayer area and biobed. Storage between bunded sprayer area and biobed beneficial - probably minimum 1 m3. Gives flow control and dilution to biobed. Pump from tank supplies liquid to biobed through drip irrigation 400 mm spacing in pipe and row width for even distribution. Float switch and time control ‘manage’ system to apply 2-4mm/ day to biobed In 600-700 mm rainfall conditions, biobed moisture appears stable. Biobed- if lined Directs all water to secondary storage or direct to field disposal area via drip irrigation as per biobed. Similar systems and controls manage application.

Is a lining to the Biobed needed? Linings were used in the trials these allowed study of the liquid flowing. Site surveys considering soil types, watercourses and drains will suggest the need for a lining. In theory pesticide Handling areas not being used for sprayer washdown may not require a lining There is a reduced load Disposal is not taking place There will be natural dispersal of liquids to the soil strata. BUT future regulatory uncertainties = if in doubt use a lining A lining will be required where washdown is to be practised. It may be beneficial anyway to control all liquid flow in order to manage the distribution to a disposal area.

Winterisation All parts of any Biobed system must be protected against frost. Maximise protection by below ground installation No serious problems were found in the research study. Above ground pipe runs should be laid to allow drainage as far as possible and can be insulated. Turf cover may assist protection of drip lines on biobed. Disposal area may benefit with a straw covering.

Biomix production and maintenance The Biomix 50% by volume straw, 25 % soil, 25% peat free compost Premixed and composted for 5-6 weeks prior to installation When installed turfed over to increase biological activity. Mixing is simple-layering on concrete-mixing with tractor loader and composting. Natural activity in the mix causes the mix to shrink Each year a topping up of the same mix is required-approx. 300 mm depth top up is needed. Other organic materials may be appropriate, not trialled yet in UK.

Long term biomix issues Swedish research suggests 6-8 year life of topped up biomix. Disposal subsequently has been to land - AFTER ONE YEARS FURTHER COMPOSTING. No pesticides have been determined after that period UK studies have not run for this time scale. Disposal if Biomix in UK will be subject to Waste Disposal Legislation. Contact Environment Agency, SEPA, EHS NI for guidance.

Useful Scientific References

Practical Simple Solutions Protecting the Environment Reductions of 10,000 to 100,000 fold in pesticide concentration on discharge Practical Simple Solutions Protecting the Environment CAUTION Seek Regulatory Advice Before Building a Biobed Contact the Environment Agency's Agricultural Waste Line 0845 6033113