New policy brief: Targeted measures are needed to reduce nitrogen loads effectively
A recent modelling study of Danish watersheds shows that the combined, nation-wide measures of limiting fertilisation rates, improving manure use and mandatory catch crops, as well as the measure of setting aside some of the arable land, has led to significantly reduced nitrogen losses to the aquatic environment. However, it took 8–10 years for the measures to reach their full effect, due to legacy effects, largely caused by nitrogen bound in soil organic matter.
To meet the goals of halving nitrogen losses from agriculture and reducing eutrophication in the Baltic Sea, however, such general regulations will not be enough, concludes the researchers behind a new policy brief. In addition, more targeted measures are needed to areas with high risk of nitrogen leaching.
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The authors also provide a set of recommendations targeted to decision-makers and managers:
- Harmonise, facilitate and require nutrient accounting at the field level. Support soil nutrient mapping and precision-agriculture.
- Subsidise cost-effective, targeted measures (e.g. catch-crops, buffer zones and wetlands) based on high-resolution risk maps for nutrient losses established by reference scientific institutions.
- Incentivise agro-ecological and circular practices, in particular the local co-dimensioning of livestock herds and manure quantities, with the crop demand and soil nutrient status.
- Invest in infrastructure and equipment, and promote knowledge transfer for best practices to improve the nutrient utilisation from manure and prevent atmospheric losses.
- Evaluate the effect of policies over the long-term to allow for legacy effects to subside.
Read the full policy brief here:
Effective reduction of nitrogen loads requires targeted measures (pdf version)
(PM Stockholm University, gek.)