Compost of poultry manure and olive mill wastes as an alternative fertilizer

We studied a compost made of poultry manure, olive mill wastes and mineral-rich wastewater, as an alternative fertiliser. The composts were of high quality, characterized by high levels of nutrients, a relatively low C/N ratio of 15-17 and a fertilizing value similar to that of conventional cattle manure, however without phytotoxicity. Field experiments showed an increase in potato production of 31.5-35.5 t/ha, compared to 30.5 t/ha using cattle manure. The use of olive mill wastewater did not have any negative impact on soil pH, electrical conductivity and phenols. The compost made of poultry manure and olive mill by products appears therefore as a promising ecological alternative to classical fertilizers.