Resumen
Fertilizer prices have risen worldwide since the end of 2021. In this context, the value of organic fertilizers has also changed from the farmers? perspective. Hence, an open question about their value arises with an increased demand for organic fertilizers. This question must be addressed individually for each farm. Hence, a linear optimization model is applied. The model can be adapted to farm conditions and provides mineral and organic fertilizers as plant nutrition variables. The price level at which an organic fertilizer becomes competitive within the farm can be identified by parameterizing the organic fertilizer prices. This substitution value marks the maximum price a buyer could pay for a particular fertilizer. This method is repeated in the study in different scenarios. For an exemplary digestate (N-P2O5-K2O = 5-2-5 kg per ton), substitution values between EUR 1.70 and EUR 16 per ton could be determined, excluding transport and application cost. This study provides a basis for a decision support system that farmers can use to determine the value of organic fertilizers. As a positive implication, it can be expected that organic fertilizers will be used where they contribute best to value creation.