The study looked at the relationship between the chemical makeup of soil humus and various factors in tobacco-growing regions in China. They found that carbon content in the soil humus varied between regions, with higher levels in southeast China. The ratio of humic acid to fulvic acid in the soil was also higher in southeast China compared to other regions. Paddy soil had the highest carbon levels and humification degree. Additionally, soil pH was negatively correlated with humus composition, and alkali-hydrolyzable nitrogen content changed based on the ratio of humic acid to fulvic acid in the soil.