Diagnosis of the fertility of compost-based growing media: Method comparison and monitoring in pot plant cultivation

• New correlations have been established among growing media fertility methods using different substrates in actual field conditions.
• There was a correlation between the water extract method and the induced percolate method.
• For all parameters, there was a correlation between leachate method and induced percolate method.
• Induced percolate method is a reliable tool for monitoring substrate fertility of compost-based growing media.

Using compost instead of peat as an ingredient in substrate mixtures is a way of increasing the sustainability of pot plant nurseries. However, this use should also include monitoring to assess crop fertility, given that compost generally has a high fertilizer content. Of the different monitoring methods, the most effective, objective and preventive one involves monitoring the nutrient status of the substrate. The main objective of this study was to provide evidence-based information on fast methods used in the field to characterize substrate fertility compared to a water extract method in order to apply these methods in cultures with unusual alternative substrates.We observed a high level of agreement between the concentration of nutrients measured using the IP method and the concentration using the fertility assessment methods most commonly used in horticulture (leachate and water extract methods). By using different compost-based substrates and comparing them to a control substrate, we have shown that the IP method is useful for monitoring substrate fertility in pot plants. Results show that the IP method indicates the nutrient composition of the functional part of the different substrates (root zone) and their development. The induced percolate method is a useful, nondestructive field method for quickly checking the nutrient content of the functional part of substrates.