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Nutrient Management & Symbiosis

Soil fertility and plant symbioses are central to plant nutrition in organic farming. A fertile soil is in good physical, chemical and biological condition and can fulfil its ecological functions. Symbiotic root fungi (mycorrhiza) particularly promote phosphorus uptake by plants, while nodule bacteria, which live in symbiosis with legumes, make an important contribution to the nitrogen balance. In mixed organic farms, the nutrient cycle between plants and animals is closed as far as possible. However, with every product sold, nutrients are removed, which can cause the soil to become impoverished in the long term. In order to close the nutrient cycle between society (waste, sewage sludge) and agriculture, technologies are required that meet strict hygiene requirements as well as the nutrient and pollutant content of the recycled fertilisers. Additionally, they need to comply with the requirements of organic farming.

We are currently investigating several aspects of nutrient management, including:

  • How can the biological fixation of nitrogen via symbiosis of nodule bacteria and legumes be used optimally?
  • What are the advantages of promoting root fungi in terms of soil structure, phosphorus uptake and resistance to drought?
  • How can the demand for nitrogen be met during phases of intensive plant growth when the supply from the soil is insufficient?
  • Can biochar reduce gaseous nitrogen emissions and losses from nitrogen leaching into the environment?
  • Can the use of recycled fertilisers help avoid a structural dependence of organic farming on conventional animal husbandry?


Else Bünemann-König