Impact of management intensity of agricultural systems and soil intrinsic characteristics on soil organic carbon stocks

Enhancing carbon in soils is crucial for improving soil health and building sustainable agroecosystems. Inherent SOC stocks are site-specific and vary due to complex interactions between climate, soils, land use, and management practices. However, the coupled effects of these factors on SOC dynamics are not fully understood. This research aimed to evaluate the impact of different management regimes and intrinsic soil characteristics on SOC stocks and identify pathways that can boost carbon sequestration in agricultural soils. This study relied on data of 143 soil profiles distributed across the south of Ireland. Each site was sampled at four depths (0–15, 15–30, 30–45, and 45–60 cm) and characterized according to the land use and management practices implemented over the past five years. A Regression Tree (RT) model was employed to estimate the single and combined contribution of key soil properties and management practices on SOC stocks. Overall, intrinsic soil characteristics, especially the presence of humic layers and clay, are decisive to determine the SOC storage potential in soils. Land use and management practices primarily impact the top 15 cm, and their accumulated effect (e.g. stocking rates in grassland systems) can shift SOC stocks trends over time. Finally, the heterogeneity in subsoils controls the variability of SOC stocks in depth. The outcomes of this study can help tailor carbon farming strategies to boost carbon sequestration accounting for specific soil conditions.