This dataset presents experimental results from a large-scale field soil sampling campaign conducted across China between 2020 and 2021. The template includes the longitude and latitude information of each sampling site, along with experimental data on organic carbon content, which comprises total soil organic carbon (SOC, in g-C·100g⁻¹), water-extractable soil organic matter (DOC, in mg-C·g⁻¹), and water-extractable soil black carbon (DBC, in µg-C·g⁻¹). Additionally, the dataset provides the chemical composition of organic matter based on ¹³C-NMR analysis, including the relative abundances of alkyl C (chemical shift: 0–45 ppm, in %), N-alkyl or methoxy C (45–60 ppm), O-alkyl C (60–95 ppm), di-O-alkyl C (95–110 ppm), aromatic C (110–145 ppm), O-aromatic C (145–165 ppm), and carboxyl and carbonyl C (165–210 ppm). Furthermore, several physicochemical parameters were measured, including soil pH, soil clay content, and the relative abundance of soil mineral elemental content.