Closing the loop in the free-range management of laying hens: Substrates & Additives for the Close Range „KLUFT“ (2019 – 2025)

Project Objective: The overall objective of the project is to capture the high nutrient loads generated in the free-range management of laying hens in the area close to the house and to make them usable by using substrates and aggregates. In the sense of closing the cycle, the nutrients are to be made available for on-farm utilization, thus minimizing nutrient losses and the associated environmental pollution.

Project structure: In two exact trials (2019/20 and 2020/21), different substrates and aggregates will be tested for their ability to reduce nutrient inputs in the underlying soil (work package 1). Based on the findings of the first exact trial in 2019/2020, the use of selected substrates on practical farms will be tested in the second project year under the nutrient aspect (work package 2) and the animal welfare aspect (work package 3). For the successful implementation of the substrate application, the economics of the process will be investigated (work package 4) and a successful transfer of the project results into practice will be aimed at (work package 5).

In the project extension, additional investigations of specific substrate properties and qualities are to be carried out in a laboratory test (work package 6). Here, for example, wood chips in various sizes/grades of hardwood and softwood will be examined for their physical and chemical properties, as well as their nutrient holding capacity. Newly added are gas measurements of climate-relevant gases in real time (work package 7). These are to be measured both in another exact experiment (work package 1) and on practical farms (work package 2).

Work packages:

1. substrate tests

• Investigation of different substrates and aggregates in three exact trials (2019/20 and 2020/21 as well as 2023/24), in which the near-stall area is simulated over one seepage period each.
• Determination of Nmin dynamics, N and P balance as well as moisture in the soil under the substrate layer
• Investigation of the nutrient sorption capacity of the substrates
• Development of a management tool for practical use to assess the nutrient situation in the area close to the barn with the help of nitrate rapid test methods.

2. testing of substrates under practical conditions

• Use of selected substrates in the near-stall area of practical farms over the seepage period 2020/21
• Determination of Nmin dynamics as well as N and P balance in the soil under the substrate layer

3. animal welfare (completed)

• Literature research, expert and practitioner surveys on substrate use in weather-exposed outdoor environments.
• Use of selected substrates in the near-stall area of practice farms over the seepage period 2020/21:

- Photo documentation of animals handling the substrate - Assessment of footpad health - Investigation of parasite pressure.

4. economic aspects

• Economic calculation (cost-benefit analysis)
• Estimation of social benefits of substrate application through reduced environmental impact

5. transfer and implementation

• Publications in scientific journals and agricultural print media
• Presentations at symposia and in the context of training courses
• Workshops with experts and at conferences

6. testing of different substrate qualities (laboratory)

• Literature research on physical and chemical properties of selected substrates of different origin
• Testing of selected substrates of different origin on different physical and chemical parameters
• Testing of substrates for their water or nutrient holding capacity (laboratory)

7. measurement of emissions

• Measurement of the gases N2O, NH3, CH4 and CO2 in real time (mid- or near-infrared spectroscopy)
• Determination of the emitted gases in the substrate test
• Measurement of the gases in the close-up area of laying hen runs (practice)

https://www.oekolandbau.de/landwirtschaft/oekologische-tierhaltung/oekologische-gefluegelhaltung/legehennen/wie-lassen-sich-naehrstoffueberhaenge-im-legehennen-auslauf-vermeiden/

• Deerberg Fra, Deerberg Fri, Delics B & J Heß (2020): Kies und Schotter eine Abfuhr erteilen. DGS Magazin für die Geflügelwirtschaft, special issue in DGS 49/ 2020, pp. 8-10.
• Delics B, Deerberg Fra, Lanvers L, Seibold T, Ball L, Deerberg Fri & J Heß (2021): The laying hen run under the nutrient aspect - possibilities and limits Article in the conference reader of the 25th International Bioland Poultry Conference, online format, 10.03.2021.
• Deerberg Fra, Delics B, Deerberg Fri & J Heß (2023): What can woody strips contribute to nutrient management in poultry runs? Contribution to the conference reader of the 27th International Bioland Poultry Conference, Tambach-Dietharz 28.02.2023-02.03.2023
• Deerberg Fra, Delics B, Deerberg Fri & J Heß: Nutrient inputs in the vicinity of laying hen runs - mineral substrates are not the yellow of the egg. Proceedings, 17th Scientific Conference on Organic Farming, Gießen 05.03.2024-08.03.2024
• Deerberg Fra, Delics B, Lanvers L, Seibold T, Zublewitz S, Deerberg Fri & J Heß: Nutrient management in the laying hen run. Second BZL consultant conference, operational possibilities for water protection and water management, Neudietendorf 22.04.2024
• Heß J, Deerberg Fri, Delics B & Fra Deerberg: Shit happens: Nutrient problems in free-range laying hens and their solutions. Proceedings of the 31st Free-Range Conference and 43rd IGN Conference of the University of Natural Resources and Life Sciences Vienna, Vienna 26.04.2024
• Deerberg Fra, Deerberg Fri & J. Heß (2025): Nutrient inputs in laying hen runs - risk or resource? DGS magazine for the poultry industry 08/2025
• Deerberg Fra, Deerberg Fri & J. Heß (2025): Problem zone near the barn. Farmers' Journal 19/25, May 2025, 42-43
• Deerberg Fra, Deerberg Fri & J. Heß (2025): Pellets retain nutrients. Bioland trade magazine July 2025, 40-41

Presentation of the KLUFT project - Closing loops in the free-range management of laying hens
Eco-Field Days Ditzingen 14.-15.06.2023
www.gefluegelnews.de/article/kreislaufe-bei-der-freilandhaltung-von-legehennen

on the subject:Practical tips for free-range laying hens: Why gravel and sand fail in the chicken run

Link to the project film