The role of organic amendments to soil for crop protection: Induction of suppression of soilborne pathogens

Application of external organic inputs to soils can be considered as one of the most ancient strategies in agriculture, and it has been commonly used since the very beginning of human-based agricultural practices. During all this time, application of several organic matters to agricultural soils has demonstrated their benefit to plants and soils. Organic amendments have proved to be useful in recovering soil properties, improving soil quality and, in some cases, can be directly involved in providing beneficial effects to plants. All these obtained effects finally lead to an increase in crop protection and sustainability. One most expected effect caused by the application of organic amendments, is the suppression of a wide range of soilborne pathogens (mainly bacterial and fungal pathogens) due to the induction of physicochemical and biological changes in soils. In order to get insight into the nature of the induced soil suppression of soilborne plant pathogens, the analysis of the physical, chemical and the microbial changes, pointed to the key role of beneficial activities produced by soil microorganisms finally adapted to the environmental changes produced by the influence of organic amendments. As shown in the case studies reported here, participation of soil microbes specifically selected after organic amendment is crucial in the control of fungal soilborne diseases. Moreover, the development of omics approaches allowed these recent studies to go one step further, revealing the main actors involved in the induced soil suppressiveness and their activities. Thus omics techniques will help to understand the soil and its microbiome as a whole system, and to assign the important roles of its biological components.