Engineered sediment-based technosols amended with compost: a pathway to recarbonize compacted soils and restore agricultural functionality

The management of dredged riverine sediments represents a significant environmental challenge due to the massive volumes generated annually [1]. Reusing these sediments as agricultural amendments offers a promising opportunity to improve crop yields and plant quality [2]. In the Guadalquivir marshlands (Seville, Spain), soils also face severe physical constraints due to their clay-rich texture and low soil organic carbon content. In this context, targeted organic amendments, such as plant-based composts, are proposed to enhance nutrient availability and overall functionality in formulated Technosols.

Within this context, a six-month field trial was established in a fine-textured soil near the Guadalquivir River, characterized by compaction and poor drainage, under the framework of the SARECO Project, which formulated Technosols through the co-application of two riverine dredged sediments from the Guadalquivir River (supplied by the Port of Seville) and green compost, mixed with the native soil, as a strategy to restore soil health. Winter wheat was cultivated, and over the six-month period (until harvest) we monitored soil physical properties, organic matter composition and respiration rates, carbon dynamics, and crop productivity.

The results showed that the Technosols significantly improved soil physical properties, with lower soil bulk density and penetration resistance. These improvements were accompanied by sustained organic carbon enrichment throughout the trial. Soil respiration rates increased initially in the Technosols but declined over time. The combined application of sediments and compost produced a synergistic effect on yield, exceeding the control in grain weight and grains per head, while total biomass and protein content remained comparable to the control soil.

Overall, these findings confirm that combining riverine dredged sediments with organic amendments in fine-textured, carbon-poor soils is a sustainable strategy that increases soil organic carbon stocks while maintaining competitive crop yields. This approach provides a viable pathway for dredged-sediment valorization and the restoration of degraded agricultural soils.

REFERENCES

[1] Renella, G. Sustainability (2021), 13(4),1648.

[2] De la Rosa, J. M., Pérez-Dalí, S. M., Campos, P., Sánchez-Martín, Á., González-Pérez, J. A., & Miller, A. Z. Agronomy (2023), 13(4), 1097.

ACKNOWLEDGEMENTS: Authors gratefully acknowledge CSIC for funding the SARECO project (COCRE24015; CSIC COCREA 2024 – circular economy call). RES2SOIL project (PID2021-126349OB-C22) and P. Campos (PTA2023-023661-I) thank funding from MICIU/AEI (10.13039/501100011033) and the EU (FEDER, NextGenerationEU/PRTR) We thank Verónica Asensio and Rubén Leboreiro for their support, and Antonio Bejarano Moreno (Autoridad Portuaria de Sevilla) for providing access to the field plot area.