Abstract

Soil organic carbon (SOC) fractions, such as particulate organic carbon (POC) and mineral-associated organic carbon (MAOC), are critical for understanding soil carbon dynamics and sequestration potential. This article explores the use of mid-infrared (MIR) and nuclear magnetic resonance (NMR) spectroscopy to quantify SOC fractions in agricultural soils across diverse climate zones. MIR spectroscopy was employed for rapid, cost-effective analysis of SOC composition, while NMR provided detailed structural insights into carbon pools. Results showed that MIR accurately predicted POC and MAOC contents (R² = 0.85–0.92), with NMR confirming molecular compositions. Clay content and climate influenced fraction distribution, with temperate soils showing higher MAOC proportions. These techniques offer complementary approaches for precise SOC quantification, supporting carbon management strategies. Challenges include calibration requirements for MIR and NMR’s high cost, but their integration enhances SOC fraction assessment.