Lesson 1 – What is stewardship?

Stewardship explained

Operators have probably never been more aware of the need to ensure the correct use of products and to take every step to protect the environment, personnel and consumers. Active ingredients that are detected in water, or are of concern to regulators on safety or environmental grounds, are being removed from the market, while restrictions may be placed on the remaining products.

Many operators will be aware of concerns regarding certain active ingredients as a result of industry initiatives. Known as stewardship schemes, they provide best practice guidelines to follow when using active ingredients of concern to help prevent off-target contamination and loss.

It’s important to note these guidelines include measures that are not given on product labels and are additional to those.

Watercourse next to crop field

Drinking Water Quality

The main concern is certain active ingredients are being detected in some drinking water sources, surface waters and/or groundwater. The European Drinking Water Standard of 0.1ppb (parts per billion) is the maximum level that water companies must ensure is not exceeded by individual pesticides. It also states a maximum total pesticide concentration of 0.5ppb.

Drinking Water Protected Areas

Drinking Water Protected Areas (DrWPAs) are areas where raw water is abstracted from surface waters (reservoirs, rivers) and the ground (groundwater), to provide drinking water for people.

The active ingredient most frequently found in ground water is bentazone. The pesticide that has been causing most at risk issues is metaldehyde.

Go to the ‘What’s in Your Backyard’ interactive map to find water safeguard zones in your area:

WIYBY map

Movement to water

Pesticides can move from target areas to water in three ways:

  1. Movement from soil to water as run-off or drainflow
  2. Movement from soil to water through soils
  3. Spray drift and direct spraying of watercourses.

Drainflow losses occur when products move through the soil and into watercourses. This can occur when:

  • 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.

Run-off occurs when products are applied to soil that is compacted, saturated or frozen and, particularly, when rain falls soon after the application. Pesticides are washed off the soil surface into watercourses, either in soil solution or attached to soil particles.

A key factor influencing run-off from fields is the positioning of tramlines in relation to slopes in fields, to prevent them acting as gutters.

Tramline filled with rain water

Look out for leaching

Applied products can also move into groundwater by leaching down through the soil profile. Losses to groundwater are likely to be highest with active ingredients that have relatively high solubility and mobility.

Soil texture will also have a significant impact, with higher losses on:

  • Sandy soils and/or soils with low organic content (less than 1%)
  • Very dry soils with significant cracking
  • Where the water table is close to the soil surface.

Drift from target areas during applications will result in the direct contamination of watercourses. Operators must work to prevent drift and stop spraying during headland turns. Drift reduction measures (slow speed, low drift nozzles, reduced pressure and correct boom height) should be adopted when working close to watercourses, which should also be protected by buffer strips.

spray drift