4 july 2025
The use of organic fertilizers in growing media differs from the use of mineral fertilizers, such as CRFs or basic potting soil fertilizers. What are the important points to consider?
Organic fertilizers behave differently in a substrate compared to mineral variants. Their effect in growing media also can’t be compared to open field soil. Factors that may play a role include: the activity of bacteria needed for nitrogen mineralization, changes in pH in combination with the pH buffer of the substrate, and the possible development of a high ammonia concentration in the substrate. Additionally, the nitrogen mineralization rate from organic fertilizers varies and, due to various factors, is less predictable.
When composing substrate recipes, it is important to take into account the interaction and influence on the performance of organic fertilizers. Compost contributes positively to nitrogen mineralization. Other raw materials, often with a lower pH buffer capacity, can even reduce mineralization. This can affect the availability of nutrients during the culture.
In short, for the successful use of organic fertilizers, various aspects and their interactions must be considered. In summary, the dynamics around organic fertilizers can be illustrated as follows:
-750-0.jpg)
For RHP-certified organic fertilizers applied in RHP-certified growing media, product-specific maximum dosages apply. Ask your organic fertilizer supplier for the maximum permitted dosage (kg/m³) for the RHP quality mark. This dosage can vary per product. Certified organic fertilizers are periodically tested in cultivation trials according to RHP quality mark requirements to ensure the quality and safety of the products.
Would you like to learn more about the dynamics of organic fertilizers? Download the research summary ‘Dynamics around organic fertilizers’ (available in the RHP knowledge base and on My RHP under RHP research reports).
