Compost: Its role, mechanism and impact on reducing soil-borne plant diseases

•History of compost research regarding microbiology and disease suppressiveness.•Microbial community and key microbes in composting processes.•Methodologies (past and present) used to analyse microbial communities in compost.•Application of effective soil microbes for the enrichment of composts.•Potentially important role of non-culturable microbes in disease suppression. Soil-borne plant pathogens are responsible for causing many crop plant diseases, resulting in significant economic losses. Compost application to agricultural fields is an excellent natural approach, which can be taken to fight against plant pathogens. The application of organic waste products is also an environmentally friendly alternative to chemical use, which unfortunately is the most common approach in agriculture today. This review analyses pioneering and recent compost research, and also the mechanisms and mode of action of compost microbial communities for reducing the activity of plant pathogens in agricultural crops. In addition, an approach for improving the quality of composts through the microbial communities already present in the compost is presented. Future agricultural practices will almost definitely require integrated research strategies to help combat plant diseases.