Grassland Herbicide Use and Water Quality

Grassland herbicides are an important part of good grassland management for many farmers. However, misuse can lead to impacts on water quality. This factsheet was produced as part of a series of factsheets by the Agricultural Sustainability Support and Advisory Programme (ASSAP).

Download Publication (PDF)

How to Reduce Reliance on chemicals

• Use mechanical control of weeds, topping or mulching
• Reduce soil compaction due to machinery or outwintering practices
• Where appropriate maintain or improve drainage (Consult with your adviser before you carry out any works)
• Improve Soil fertility by liming, correct applications of P and K levels
• Ensure good grassland management practices e.g. rotational grazing
• Maintain dense sward cover by avoiding poaching and overgrazing

Tips to reduce the risk to Water Quality when using Pesticides

1. Assess if you need to spray – can your weed problem be resolved by non-chemical methods.
2. Ensure that your sprayer is tested, calibrated and in good working order and that the operator is a registered Professional User.
3. Use the appropriate product and follow the label recommendations on use. Apply herbicide when weeds are actively growing and at the right stage of growth. 
4. Ensure the sprayer operator is aware of the location of all nearby water bodies (ditches, streams, ponds, rivers, lakes and springs, drinking water abstraction points)
5. Do not perform handling operations (filling, mixing or washing the sprayer) near water bodies, open drains or well heads. Do not fill sprayer directly from a stream, drain, lake or pond.
6. Apply all herbicides in suitable weather conditions (no rainfall forecast, calm day with a morning or evening application in hot weather). Consider using drift-reducing nozzles when spraying.
7. Used pesticide containers should be triple-rinsed, washings added to the sprayer tank and empty containers should be disposed off correctly. Contact your Local Authority for guidance.
8. Clean and wash down the sprayer in a suitable field, well away from any water bodies or open drains.

Summary

Grassland herbicides are an important part of good grassland management for many farmers. However, misuse can lead to impacts on water quality.
Farmers should try to avoid using herbicides where possible by applying good grassland husbandry techniques. Where herbicide use is necessary, best practice advice should be followed to ensure minimal losses to water.

For more information please visit www.teagasc.ie/water-quality or view the other factsheets in the series here