The scientists analyzed soil in China to understand how much carbon it stores. They used a detailed soil map and found that China's soil holds 89.14 billion tons of carbon, with an average of 96 tons per hectare. Some soil types, like Cambosols and Argosols, store more carbon than others like Andosols and Vertosols. Histosols have the highest carbon density, while Primosols have the lowest. This information helps us better estimate and track changes in carbon storage in China.