The usefulness of a digestate from an anaerobic codigestion process as a fertiliser product was evaluated
in a field experiment using two horticultural crops (watermelon and cauliflower), during two successive
growing seasons. The effects of the digestate were compared with those of a traditional organic
amendment (cattle manure) and a conventional mineral fertiliser. Digestate addition to soil provided a
source of available nutrients (nitrogen and phosphorus) in the short-term and had positive effects on soil
biological properties such as microbial biomass and enzyme activities, compared to the non-amended
soil. The digestate application to soil led to yields comparable to the mineral fertilisation for the summer
watermelon crop. However, for the winter cauliflower crop, only plots treated with the mineral fertiliser
had good production. Nitrogen from the digestate is rapidly and highly available for plant growth in
the short-term but also can be easily lost, together with a slow rate of microbial processes due to low
temperatures, could reduce the fertilising capacity of the digestate. This seemed to be the main limiting
factor for the winter cauliflower crop, where digestate or cattle manure, used as basal dressing, were not
enough to satisfy the crop demand for nitrogen during its whole growth cycle.