Figure 6
From: Molecular composition of soil organic matter (SOM) regulate qualities of tobacco leaves

Van Krevelen diagrams of common SOM formulas. (a) Common formulas in high-quality soils. (b) Common formulas in low-quality soils. Different colors indicate common fractions between two or three samples. Different numbers on dotted box in high represent different compounds that are appropriate for both figures: ①Lipids, ② Proteins, ③ Amino Sugars, ④ Carbohydrates, ⑤ Unsaturated hydrocarbons, ⑥ Lignin, ⑦ Tannins, ⑧ Condensed hydrocarbons.