Where to go with manure and slurry?

Dossier

Gülleausbringung auf dem Feld

Regions with intensive livestock production produce a lot of manure. Manure, as well as slurry from biogas plants, is left as fertilizer on the fields. If excessively applied, nutrients can be washed out and pollute waters. What can be done about this?

Agricultural production can lead to high nutrient inputs into water bodies – these are often higher than the nutrient concentrations for surface and groundwater allowed by the European Water Framework Directive.

However, the dimension and sources of water pollution differ greatly. In Northern Germany in some regions with high livestock density, the application of manure leads to extremely high pollution rates. Additionally, due to the promotion of renewable energies, the cultivation of maize for bioenergy has increased greatly. Slurry is additionally applied on fields, whereby more nutrients from agriculture can enter soils and water bodies.

Deutschlandkarte mit Angaben zur Stickstofflieferung aus Wirtschaftsdünger inklusive Gärreste
Nitrogen inputs from manure and slurry 2014 (© Thünen-Institut/LR-eigene Berechnungen)

Research from the Thuenen-Institute and other research partners shows that current reductions of nutrient surpluses and inputs will not be sufficient to reach the good water quality standards set by the European Commission. More efforts will be necessary to reach the requirements. Among other things manure and slurry need to be exported from hot-spot regions. But how and to where? This problem needs interdisciplinary approaches, as manure needs to be distributed efficiently on the one hand, but on the other hand, the EU Water Framework Directive prohibits a worsening of the situation. One example for an interdisciplinary approach is the AGRUM Weser project which combines agro-economic and hydrologic models in a modelling network.

Current analyses from the Thuenen-Institute of Rural Studies show that some regions in Germany need to do more than just fulfil the requirements of the Fertilization Ordinance. More efforts and discussions are necessary. The assortment of possible measures – such as additional area-wide agri-environmental measures, better drainage management or the application of buffer strips- are evaluated in different projects with respect to impacts and cost.