The farming industry has made great progress in keeping pesticides out of water. We must however remain proactive in protecting water and the safe use of pesticides.
The risks from pesticides
Protecting water – A year round challenge
Key points to remember
- Work with your agronomist to identify local and catchment risks
- Identify fields, crops and situations with a greater risk of pesticides reaching surface or groundwater
- Establish grass buffer strips beside all watercourses at least 6m wide
- Review crop protection plans and identify products that may need extra considerations
- Plan your pesticide handling areas, identify nearest surface water and all drains. Eliminate any activities that threaten water.
- Ensure all drainage water / run-off from handling areas drains into a lined biobed or sump prior to disposal to an area with a groundwater permit.
- Minimise cultivations and retain surface residues to help stabilise soil structure and keep soil, pesticides and nutrients in the field.
- Minimise runoff and erosion from tramlines – cultivate across the slope and use low ground pressure tyres.
- Test all application equipment annually and maintain it during the season.
- Check weather forecast and soil conditions before spraying
- Ensure label requirements for a LERAP (Local Environment Risk Assessment for Pesticides), or a buffer zone are followed.
- Avoid spraying if soils are very dry and deeply cracked, field drains are flowing or likely to flow within the next 7 days, or heavy rain is likely within the next 48 hours.
What are the risks that could be improved?
Oil seed rape herbicides
- For example carbetamide, propyzamide and metazachlor.
- Effective application depends on balancing the threat of loss to water due to poor soil or weather conditions against correct timing for efficicacy.
- Used extensively on winter OSR, without it crop would barely be viable.
- Based on metaldehyde
- Reduce the risk of reaching water by reducing application rates and improving application techniques.
- For more information visit www.pelletwise.co.uk
Practical steps to make pesticide use safer
- train users and advisers to high standards backed-up by certification
- using alternative methods of control (keeping in mind that these may also pose environmental risks), or combining these with chemical methods
- where two or more pesticides may be equally effective, may sure that you select the one that is likely to involve least environmental risk
- working to a crop management plan based on proper risk assessments and cautious decisions
- using the most appropriate application technique, and making sure to check and calibrate equipment regularly
- disposing of containers and unused products correctly.
Pesticide losses to water
How pesticides can reach water from the yard
Losses from the yard
Around 40% of the pesticides that are found in surface water are thought to have originated from poor practice in the handling area.
Typical losses can be from spills, splashes or washings.
Image source: Every Drop Counts, Crop Protection Assocation
How pesticides can reach water from the field
- Pesticides are applied to very dry / cracked soils
- When heavy rainfall occurs within 48 hours of pesticide application
- Pesticides are applied to very wet or saturated soils and small amounts of rain flush them through the soil profile
- As a result pesticides in solution or attached to soil particles can enter the watercourse via drains or soil movement. This is a particular problem in autumn and winter and when field drains are effective.
- Occurs when pesticides are applied to compacted, wet or frozen ground, especially when rain falls shortly after application.
- Pesticides are then washed off the soil surface into the nearby watercourses.
Can occur by:
- Failure to turn off booms when turning at headlands
- Poorly placed tramlines
- Lack of grass buffer strips
- Application in windy conditions
- No buffer strip
Losses to groundwater
- Leaching through soil into groundwater
- Risks are higher where the water table is close to the soil surface
- Losses may be higher in thin sandy soils, or soils with low organic content (less than 1%) or where dry ground is cracked.
Best practice in the yard
Should be secure and frost free. They need a bund to stop leaks from spills and burst containers. Storage capacity should be adequate to handle the maximum amount. Ensure that there is first aid and fire provision also.
It is important to keep track of products delivered and used.
Design the site to handle any spills / splashes. Any surplus water should either run to a contained drainage system or a biobed. If there is only small amounts it may be ok to fill on grassland that is away from watercourses, ditches or gateways.
Ensure that the filling area is equipped for safe handling and use of chemicals and potential spillages.
Check all your equipment pre-season. Make sure that you complete relevant training for the type of sprayer that you are operating.
Washing and Cleaning
Should be undertaken well away from watercourses. Wash down in the field using a clean water tank, internal tank rinsing nozzles, and a brush and hose for the exterior. A different option is to wash down in the handling area making sure that any washings are drained to the contained drainage system or biobed.
Stocktaking and disposal
Stock take twice per year, and ensure that products are still authorised for storage and use. Dispose of any excess using an approved contractor.
Pesticide losses in soil
Reducing the impact of pesticides on the soil
- choose products that do not persist unnecessarily
- combining chemical methods with non-chemical methods for controlling pests in the soil and weeds
- accurately calibrating equipment and taking other measures to improve the targeting of pesticides
Reducing impact on wildlife
- use buffer strips to protect important wildlife features (or rings around isolated trees)
- create beetle banks and extend field margins, or use set aside land to provide new or alternative habitats
- take particular account when spraying of wind speed and direction in order to avoid spray drift
- use alternative techniques and equipment to minimise the risk of drift and improve the deposition of spray on the crop
- retain or reintroduce crop rotations, at least on part of the farm to avoid chemical build up
- use more selective and more specific pesticides
- use strategies that avoid the need for complete control of weeds and insects (for example involving pest or weed thresholds).
Best practice in the field
Use a range of control strategies
Integrate plant protection products with crop rotations, cultivations and the use of resistant varieties.
Only spray when necessary
For financial and environmental reasons.
Take account of soil and weather conditions when planning spraying activity. Do not spray when heavy rain is expected, ground is waterlogged, frozen or snow covered, or the ground is dry and cracked.
Plan field work to minimise any short workings and overlaps, Consider the use of precision technology, which will enable the shut off of a specific boom section to improve accuracy.
If it is necessary to spray beside watercourses take advantage of any opportunities to use GPS mapping and automated sprayer control to enhance protection of watercourses across the farm. Install 6m grass buffer strips next to watercourses, use wider strips up to 20m for long or steep slopes.
Optimise soil management
Managing soil correctly will reduce soil erosion and run off, and well managed soil will help protect watercourses. Maintain soil structure as far as possible and organic matter levels to stabilise the soil, and reduce rapid drainage. If subsoiling is required, only subsoil just below the plough pan depth to remove compaction and avoid subsoiling before applying any chemicals with a WPAS.
Consider the use of min till or no till, as this can help protect soils from rain drop impact.
Minimise risk of chemical movement
Create tramlines across the slope, use low ground pressure tyres and establish buffer zones to minimise the risk of movement through run off or drainflow. If slopes are steeper consider the use of beetle banks that follow the contour lines.