研究了棕壤各粒级微团聚体中有机质的腐殖质组成、胡敏酸光学性质和活化度的变化.结果表明,棕壤胡敏酸以Rp型为主,随粒级的增大,一般表现出相对色度(RF)减小,活化度提高.土壤有机培肥后,各级微团聚体中胡敏酸的比例增加,且有向Rp型或P型方向转化趋势,从而说明胡敏酸的缩合度和分子复杂程度下降,活化度提高 The humus composition, the optical properties and the degree of activation of humic acid were studied in all fractions of microaggregates of brown soil. The results showed that the brown soil humic acid was dominated by Rp, and generally increased with the increase of grain size The relative chroma (RF) decreases and the activation degree increases.After soil organic fertilization, the proportion of humic acid in the micro-aggregates at all levels increases, and there is a tendency toward Rp or P type transformation, indicating that humic acid The degree of condensation and molecular complexity decreased, and the degree of activation increased