An increasing amount of advice is being offered to pesticide users (through agronomists, subsidy providers and agricultural advisors). Public pressure is increasing on chemicals and many farmers are now looking to include more cultural pest control measures (examples below), as farming would have been before chemicals. Of course, farmers aren’t the only people to use pesticides. Pest control in back gardens and allotments can have just a big of an impact to a nearby river – so please do use pesticides responsibly (remember to always read the label).
Regulation of Use
Pesticides go through a vigorous testing procedure before they become available on the market. This ensures that they are safe to use and have no impact on the environment when used within legal safe limits. These products have to be re-registered anywhere between 5 and 25 years; occasionally pesticides are found to be unfit for use (e.g. has a previous unidentified environmental impact) and as a result their use is limited or banned.
Pesticides in Rivers
All pesticides that are used in agriculture end up in rivers in various concentrations or states. These rivers form the raw water source that we all drink. In the majority of cases, these pesticides can be removed by standard water treatment and therefore they do not pose a threat to water quality and supply. Certain pesticides are more difficult to remove during the water treatment process due to their simple structure which makes them very stable in water. Metaldehyde is one example of these difficult to treat pesticides – used widely in slug pellets both on farm and in gardens or on allotments.
The Scale of the Problem
Metaldehyde isn’t alone. A number of different pesticides are being found more often and in higher concentrations in rivers and at water treatment works (including propyzamide, metazachlor and clopyralid, just to name a few). The reason for this is obvious; as the toolbox of chemicals (or active ingredients) available to farmers decreases (with more products being removed than new ones approved), the use of the available chemicals naturally increases (as there are fewer options to pick from). This causes an increase in the concentrations found in rivers… but what other options do farmers have?
The majority of pesticides in rivers come from the farm yard, through spillages during transport, storage and filling/cleaning spreading equipment. Farmers are advised to invest in pesticide filling areas with available agri subsidies to prevent this possible pollution source.
Here are some additional options to reduce reliance on chemical pest controls:
- Reducing favourable environments for pests
- Cultivating and destroying weeds before a crop
- Managing soils to minimise weed establishment
- Increasing natural predator numbers
- Changing crop timing to when pest pressure is low