黑粘土腐殖质的组成和特性

A STUDY ON COMPOSITION AND CHARACTERISTICS OF HUMIC SUBSTANCES IN BLACK CLAY SOILS

采用波诺马廖娃等修改的丘林法，研究了分布于我国暖温带南沿黑粘土的几个典型剖面腐殖质组成和胡敏酸光密度指数的剖面分异特征。讨论了黑粘土的暗色成因。

The composition,contents and optical,properties of humus from several typical profiles of black clay soils in temperate zone of China were studied.The results show that HA2(black humic acid)is the main fraction of humic acid,HA-3 is the secondary and HA-1(brown humic acid)only exists in plowed layer(or epipedon) with small amount.Black humic acid is relatively enriched in black soil horizon. According to the optical density index and colour of their solutions, the aromaticity of HA-2 is quite high, that of HA-3 is lower, and both of them are higher in black soil horizons than in other horizons.Ec appears more suitable than E4/E6 in expressing the aromaticity of humic acid.Although physical and chemical properties have been changed largely in white solonetz,which was formed from black clay soil, features of its humus didn's change on the whole.In addition,the cause of formation for darkness of black clay soil and for vertical change of contents and properties of humus fractions in soil profile,the origin of humus in soil and the relationship between properties of humus and soil fertility were discussed.