Workshop on organic recycled materials to improve soil fertility in vegetable production

The workshop was organized by the two Danish partners Department of Food Science at Aarhus University and HortiAdvice. The 16 participants represented vegetable growers, consultants and researchers.

The morning program set the scene by presenting challenges, research results and practical experiences in agriculture and vegetable production:

• Professor Lars Juhl Munkholm, Department of Agroecology - Soil Biology and Nutrients, Aarhus University: Danish challenges with soil health and sustainable cultivation methods. 
• Consultant Richard de Visser, HortiAdvice: Vegetable growers' difficult path to fertile soil.
• Associate Professor Susanne Eich-Greatorex, Norwegian University of Life Sciences, Section of Soil and Water Sciences: Experience from a long-time experiment (11 years) with organic fertilizers in cereal production. 
• Research group leader, Associate Professor Hanne Lakkenborg Kristensen, Department of Food Science, Aarhus University: Recirculating and regenerative fertilization strategies - gold grains from experiments.

After lunch, participants discussed in groups the experiences, challenges, and knowledge needs on the use of organic amendments to improve soil health while maintaining/increasing yield in vegetable production. The outcome of these discussions will form the basis for the design of the long-term field trials with vegetables and legumes (the Danish food crops showcase).

The messages from the working groups were:

1. In the trials, focus must be on maintaining commercially competitive yields so that the effects of organic amendments on soil health are measured in a realistic production setup.

2. It is very relevant to test compost based on vegetable residues, compost based on local meadow grass, plant-based biogas digestate and biochar, while sewage sludge is not considered as an ideal organic amendment for vegetable production. AU Food researchers showed strong interest on new organic amendments sources such as insect frass.

3. Crop rotation could include cabbage, onion/leek, carrot and barley-pea intercropping.

The researchers at Aarhus University will now continue planning the trials which will start in the spring. HortiAdvice will contribute with their extensive knowledge of commercial vegetable production.

CLOSECYCLE project is funded by the EU Interreg North Sea program (CLOSECYCLE | Interreg North Sea). We also thank the Danish Green Development Program (GUDP) for co-funding.