Optimizing Carbon Sequestration in Croplands: A Synthesis

• Main Authors: Alexandra Tiefenbacher, Taru Sandén, Hans-Peter Haslmayr, Julia Miloczki, Walter Wenzel, Heide Spiegel
• Format: Article
• Language: English
• Published: MDPI AG 2021-04-01
• Series: Agronomy
• Subjects: 4-per-mille initiative; agricultural soil management practices; climate change adaptation; climate change mitigation; long-term experiments; soil organic carbon (SOC) stock
• Online Access: https://www.mdpi.com/2073-4395/11/5/882

Climate change and ensuring food security for an exponentially growing global human population are the greatest challenges for future agriculture. Improved soil management practices are crucial to tackle these problems by enhancing agro-ecosystem productivity, soil fertility, and carbon sequestration. To meet Paris climate treaty pledges, soil management must address validated approaches for carbon sequestration and stabilization. The present synthesis assesses a range of current and potential future agricultural management practices (AMP) that have an effect on soil organic carbon (SOC) storage and sequestration. Through two strategies—increasing carbon inputs (e.g., enhanced primary production, organic fertilizers) and reducing SOC losses (e.g., reducing soil erosion, managing soil respiration)—AMP can either sequester, up to 714 ± 404 (compost) kg C ha⁻¹ y⁻¹, having no distinct impact (mineral fertilization, no-tillage), or even reduce SOC stocks in the topsoil (bare fallow, business-as-usual). AMP can sequester between −20 ± 210 (mineral fertilization) and 714 ± 404 (compost) kg C ha⁻¹ y⁻¹ in the topsoil. No-tillage practices have no distinct impact, and bare fallow or “business-as-usual” scenarios even reduce SOC stocks in the topsoil. Overall, the carbon sequestration potential of the subsoil (>40 cm) requires further investigation. Moreover, climate change, permanent soil sealing, consumer behavior in dietary habits and waste production, as well as the socio-economic constraints of farmers (e.g., information exchange, long-term economic profitability) are important factors for implementing new AMPs. This calls for life-cycle assessments of those practices.