However, humin has been the least studied of all humic fractions, mainly because of its insolubility, inhomogeneity, and structural complexity.

• 提出近期的研究重点主要包括：(1)比较不同分离方法获得的土壤胡敏素的差异，以达到方法上的可比性和统一性，同时提出更适宜的分离方法；