At the 18th Scientific Conference on Organic Agriculture (Wissenschaftstagung Ökologischer Landbau) in Bonn, a workshop addressed the question of how practices such as compost application, transfer mulch and cover crops can contribute to improved water-use efficiency in vegetable production systems. The session began with short inputs from Margita Hefner (IGZ), Benjamin Ruch (Kassel University), Christian Bruns (Kassel University) and Esther Pfeifer (LLH), who presented current research and practical perspectives on irrigation systems and soil-based strategies for water management.
The subsequent discussion took place in the plenary group and was moderated by Christiane Weiler (Kassel University, HydroSoilWise project). Participants collected their ideas and observations on cards, which were then clustered on pinboards. These clusters reflected several recurring themes in the discussion.
Soil management
One cluster focused on the role of soil management. Participants emphasized that improving soil structure, biological activity and organic matter content is central to better water retention and infiltration. Measures such as mulch application, compost use and cover crops were frequently mentioned. Some cards also highlighted the importance of biopores, root systems and living soil processes for stabilizing soil moisture.
Crop management and system approaches
Another cluster addressed cropping strategies. Participants discussed planting dates, crop selection and crop rotations as factors influencing water demand and system resilience. Cover crops and diversified cropping systems were considered promising approaches to stabilize soil moisture and reduce drought stress.
Irrigation strategies and technical solutions
A further cluster related to irrigation technologies and management. Suggestions included targeted irrigation, partial-area irrigation and the use of digital tools to support irrigation decisions. However, the discussion also stressed that technical solutions need to be combined with soil-improving measures to be effective.
Barriers to implementation
Participants also clustered several cards around practical constraints. Key barriers included costs, labour requirements and the maintenance effort associated with irrigation systems and new technologies. In addition, limited water availability, weather variability and uncertainty about the effectiveness of certain practices were mentioned.
Knowledge transfer and framework conditions
Finally, a cluster addressed structural and institutional factors. Participants highlighted the importance of advisory services, exchange between farmers and researchers, and supportive policy frameworks. Improving knowledge transfer between research, extension and practice was seen as crucial for the wider adoption of water-efficient production practices.
Overall, the clusters showed that improving water-use efficiency in vegetable production is not only a technical challenge. It requires an integrated approach combining soil management, cropping strategies, irrigation practices and effective knowledge transfer.