Closing the loop in free-range laying hens: Substrates & aggregates for the close range "KLUFT" (2019 - 2025).

Closing the nutrient cycle in the run of free range layers – suitable enrichment materials and additives
Laying hens kept in free range housing systems are to have access to an outdoor run. Due to the animals’ specific behavior and their preference of areas close to the stable these areas often show high accumulation of nutrients. The project’s major aim is to test different enrichment materials/litter and additives for their ability to absorb nutrients.  Nutrients are to be made available for on-farm utilization, thus minimizing nutrient losses and the associated environmental pollution.  


"Optimization of free-range management of laying hens to reduce nutrient inputs in the run in a participatory approach with the practice" (OPAL).

Optimizing free range housing systems of laying hens in order to reduce nutrient accumulation int the outdoor run in a participatory approach with farmers

Despite numerous design and management concepts for laying hen runs, areas close to the stable often prove to be highly affected by nutrient accumulation.
The transdisciplinary project, which is funded by the Deutsche Bundesstiftung Umwelt (DBU), therefore aims to develop solutions with farmers in order to reduce nitrogen inputs to the soil.


  • Nitrogen inputs in free-range laying hens
  • Nitrogen dynamics
  • Nutrient sorption capacity of different substrates
  • Nitrogen emissions in poultry runs