Soil microbial communities as drivers of health and resilience in Mediterranean dryland agriculture

Abstract

Agriculture in Mediterranean ecosystems faces significant challenges. One of the most relevant includes soil degradation; due to soilis a non-renewable resource on human timescales. As a vital component of the soil ecosystem, the soil microbiome plays an essential role in maintaining fertility and is used as a key ecological indicator of soil health. Comparing biological indices of soil quality such as the dynamics and diversity of microorganisms in sensitive ecosystems like drylands under different agricultural, forestry, and grazing practices, could support decision-making and the selection of sustainable management practices to improve soil quality and resilience to climate change [1]. The proposed study involves 460 sampling paired sites –two nearby locations with different land uses– across Spain, Croatia, Turkey, Greece, Tunisia, Morocco, France, Algeria, and Italy, collecting topsoil samples (0-20 cm). The goal is to obtain microbial indicators and study the microbial population dynamic by using i)DNA-based massive sequencing, ii)phospholipid characterization (PLFA) for taxonomic identification, and iii)enzymatic activity assays to assess functional groups. Initial analyses have been conducted on a subset of samples (mainly woodlands, and olive tree plantations; in Andalusia, south of Spain ), focusing on enzymatic activities. The results showed higher activities of β-glucosidase, acid phosphatase, and L-leucine aminopeptidase in woodland soils, probably linked to a more diverse and active microbial community, less impacted by pesticide application compared to the olive tree farm. Conversely, we obtained lower arylsulfatase activity in woodland soils, that may be influenced by specific soil properties, such as the presence of rocks, which could affect sulfur cycling and enzyme function [2]. This integrated approach will provide valuable insights into soil health across the Mediterranean basin.

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