Exploitation of natural resources to increase soil health: BIO-INCROP, a project on organic fruit tree cropping systems

Introduction The vast majority of apple production in Europe takes place in intensive orchards, this implies the need for intensive capital investment for support structures which then have to be used for a number of generations of trees. Consequently new orchards have to be replanted in the same place as previous plots. This causes soil sickness or yield decline of which “replant disease” is the main biological component. Resulting yield losses are difficult to assess; a recent study in South Tyrol, where 12% of total EU apple is produced, showed that growth reduction can vary from 20 to 60% in replanted orchard compared to fallow control. Severity of this etiology is mediated by plant vigour, physiological state of plants and abiotic factors. Therefore, its occurrence is actually an indicator for fruit growers of the degraded status of biological soil processes. The only effective strategy to control replant disease and crop decline in organic fruit tree orchards is to increase soil diversity, and consequently, the various microbial processes involved in controlling soil borne pathogens, enhancing root growth and mediating plant nutrition. Methods BIO-INCROP, an European transnational project on organic farming, aims to increase knowledge about agro-management practices based on the study of microbial factors involved in soil suppressiveness and biological soil fertility. Project activities are planned on two reference crops: apple and citrus, which represent two main European agro-environments: apple growing areas of Central Europe (Switzerland, Germany, South Tyrol in Italy and Styria in Austria) and Mediterranean citrus growing areas (Valencia region in Spain and the East Mediterranean region of Turkey). Research Actions of the project focus on exploitation of two main categories of natural resources in order to develop innovative cropping practices which will enable soil biodiversity preservation and exploit its biological features. They are: 1. Biological resources indigenous to the orchard soil represented by microbial communities and wild plants of natural vegetative covers. 2. Natural resources exogenous to the orchards; in particular, recycled organic materials and cover crops chosen from local germoplasm collections and wild plants. Early evaluation of soil health based on plant response in greenhouse bioassay tests and culture-based and molecular methods for microbial response evaluation, are the integrated methodologies used to identify natural resources and techniques capable of increasing microbial biomass and diversity and selectively affecting beneficial and pathogenic microbial populations. Each country’s activities is planned in close cooperation with regional agricultural research centres working on organic farming and laboratories with specific expertise. Expected results The main objectives and expected results of the project are: 1. To provide indicators of degradation status and risk for replant disease occurrence in the orchards. 2. To promote the use of indigenous or external resources for developing innovative management options aimed at i) selectively increasing the components of soil suppressiveness, ii) preserving and increasing soil microbial biomass and diversity. 3. To integrate the national guidelines for certified organic production with agro-management strategies based on eco-functional intensification of organic cropping systems. 4. To provide knowledge for supporting: i) critical adoption by farmers and local extension services of available organic amendments and bio-products ii) the development of soil management practices aimed at increasing soil suppressiveness according to available natural resources and environmental conditions. Financial support for BIO-INCROP project provided by the CORE Organic II Funding Bodies, being partners of the FP7 ERA-Net project, (project no. 249667)