图4. 土壤腐殖质形成土壤团聚体的两类模式^[9,13]
A模式：土壤团聚体由长链的胡敏酸物质与土壤颗粒结合形成。B模式：土壤团聚体由腐殖化产生的多元化的短链物质构成,这些短链物质有多糖（黑色）、多肽（蓝色）、脂肪族化合物（绿色）和多环的木质素碎片（褐色）。这些短链物质通过阳离子（红色）与土壤矿物颗粒结合形成土壤团聚体

Fig. 4. Two models of soil aggregates formed with soil humus
A Model: Soil aggregates are formed by combination of long-chain humic acids with soil particles. B Model: Soil aggregates are composed of various short-chain substances produced by humification, such as polysaccharides (black), polypeptides (blue), aliphatic compounds (green) and polycyclic lignin fragments (brown). These short-chain substances are combined with soil mineral particles by cations (red) to form aggregates