Row and inter-row management drives spatial variability in SOC and soil fauna in Mediterranean orchards and vineyards

Soil Organic Carbon (SOC) is critical for soil health and climate change mitigation. In Mediterranean orchards and vineyards, management practices vary both within fields (e.g., grass cover vs. bare soil in inter-rows) and between fields (e.g. drip vs. microsprinkler irrigation) creating complex spatial patterns. Yet, most modelling approaches assume plot homogeneity when simulating carbon and water budgets at field scale. Furthermore, existing studies often sample inter-rows alone, assuming they represent whole-field dynamics. This homogeneity assumption may introduce biases in SOC stock estimates for perennial systems, at the field level, by ignoring row vs. inter-row management differences.

This study aims to (1) quantify intra-field variability in SOC content and soil biology abundance and activity between tree rows and inter-rows, and (2) assess how this spatial heterogeneity affects model predictions at field scale.

Field data were collected in 2024 and 2025 from 19 plots in a small Mediterranean watershed in southeastern France, including vineyards and orchards with various agricultural practices and soil characteristics. Soil samples (0–30 cm depth) were analyzed for chemical (SOC, nutrients, pH), physical properties (texture) and microbial biomass, to compare row and inter-row dynamics. In 2025, earthworm and enchytraeid communities were sampled. Additionally, farmer interviews were conducted to document on history of the fields (fertilizer inputs, irrigation, soils). A multivariate analysis (PCA) identified key drivers of row/inter-row differences, with preliminary results indicating significant variability in SOC and soil biology (earthworms, enchytraeids, microbial biomasses) linked to grass cover management (p < 0.01). Linear modelling was developed to upscale inter-row measurements to whole-field estimates. These findings inform management strategies that enhance SOC sequestration while optimizing productivity and biodiversity in Mediterranean perennial systems.