Sustainable soil management in olive orchards: effects on telluric microorganisms

Soil microbial communities play several important ecological and physiological functions (soil organic matter decomposition and control of its cycle; regulation of mineral nutrient availability; atmospheric nitrogen fixation; formation of mycorrhiza; production of biologically active substances able to stimulate plant growth; etc.) ameliorating soil physical and chemical conditions and, consequently, soil habitability for plants. There is a growing interest in maintenance of the agro-system functionality. It seems that soil microbiota, particularly its biodiversity, allows the agro-systems to better overcome natural and anthropic perturbations improving their recovering capacity (resilience concept). Soil quality loss occurs especially in lands subjected to intensive agricultural practices and to an indiscriminate use of external input (fertilizers, pesticides, irrigation water). This is the reason why the optimization and the innovation of the horticultural techniques at low impact should be stimulated. As a matter of fact, sustainable practices can allow to recover normal soil fertility levels in the agro-systems with benefits on both soil fertility and crop yield quality and quantity. Olive tree (Olea europaea L.) is one of the most important crop in the Mediterranean basin. In such wide area, olive orchard management can be very different depending on pedo-climatic and socio-economic conditions and resource availability. In this chapter, a survey on soil microbiological data of olive orchards subjected to different soil management systems applied for variable time periods under different pedo-climatic conditions are reported. Particular attention is given to the changes in the structure, dynamics and complexity of soil microbial communities to evaluate soil health status. Among the agronomic sustainable practices, the input of soil organic matter as compost is one of the most important factor affecting soil fertility. For this reason, the cases of in-situ compost production in olive groves will be discussed.