Page 35 - Green knowledge 2025

Photo: Siri Elise Dybdal
Prevent pesticides from reaching groundwater
Today, farmers have limited ability to assess the risk of pesticides leaching into
groundwater. NIBIO has now developed a tool with risk tables to support better
environmental choices.
When spraying fields, pesticides can be washed away
with surface water into streams and ditches, or they
can move downward through the soil – in the worst
case, reaching groundwater and wells. The level of
risk varies with soil type and climate.
To make it easier to choose safer alternatives, NIBIO
has developed tables showing the risk of pesticide
leaching under different soil and climate conditions.
The tables currently cover all pesticides approved for
potatoes, carrots, cereals, winter oilseed rape, apples,
and strawberries as of spring 2024. They show the
calculated risk of leaching in the main soil types
across Norwegian farming areas.
The goal is for farmers to use the tables to identify
the most environmentally friendly option among the
available pesticides for each crop.
The project arose because farmers have had little
ability to assess leaching risks. Few measures exist to
prevent such leaching, and some products carry only
very general warnings, for example, to avoid spray-
ing on sandy soils.
The first risk tables were published in 2022. Previ-
ously, data existed for five of ten soil types down to
2 m depth and only for cereals and potatoes. Feed-
back suggested that results at 1 m depth – the typical
drainage depth – would also be useful. The models
have now been recalculated with a stronger data
basis to account for combinations of soil, climate,
and pesticide use.
Overall, the picture shows that leaching risk is
­ significant in many areas, especially in regions with
low temperatures and high rainfall. Farmers are free
to use the results in their decisions and can benefit
from choosing the safest solutions.
The plan is to update the risk tables annually.
Purpose: Funding: Contact: Provide Norwegian farmers with a tool to assess the potential for pesticide leaching into
groundwater under their soil and climate conditions.
Action Plan for Sustainable Use of Pesticides, Norwegian Agriculture Agency
Research Scientist Roger Holten, Division of Biotechnology and Plant Health.
Email: roger.holten@nibio.no | Telephone: +47 915 92 762
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