Influence of the starting feedstock materials to obtain compost - deeping on microbiological characteristics and the relationship with chemical composition

The composting process of organic wastes from the agricultural and agri-food sectors not only implies different benefits related to their recycling and handling, but also due to their condition of “clean waste”, since they can contribute to obtain organic growing media alternative to peat. Moreover, these materials can show properties with added value such as biofertilizing, biostimulating and/or biocontrol capacity. In this work, different composting processes using agri-food wastes, such as vine pruning wastes, tomato wastes, leek wastes and olive mill cake have been studied to determine their suitability as growing media with potential suppressive capacity against phytopathogens. The composting process and the composts obtained were evaluated by studying different chemical properties and the microbial community (bacteria and fungi). The results indicated the suitability of these materials as growing media. The composition and quantity of some of the organic agri-food wastes used in the composting mixtures could show the suppressive capacity of the final composts, this effect being mainly related to the microbial community.