Abstract: Taking the soil under five land use types, including natural grassland (NG), tame grassland (TG), frutex and grassland (FG), frutex (FX) and arbor and frutex (AF) on hilly sloping-land with purple soils in Hengyang, South-central China, as the research object, we analyzed the composition and properties of humic substance (HS), and inquired their relationships with soil physico-chemical properties. We found that:the HS content in FG was the highest, in TG was the second, and in NG was the lowest;in HS total carbon (T-C), the humin carbon (Hu-C) content was the highest and the humic acid carbon(HA-C) was the lowest;the Humic acid carbon/Fulvic acid carbon[(HA-C)/(FA-C)] value in all the five land use types was less than 1, and in TG and FG was the highest, in NG was the lowest, the (HA-C)/(FA-C) of TG, FG, FX and AF in 0~20 cm soil layer was significant higher than that in 20~40 cm soil layer (P<0.05);the HS, HA-C, FA-C, Hu-C, soil organic carbon(SOC), alkali-hydrolyzable nitrogen(AN) and available phosphorus(AP) was significant or extremely significant correlated with each other positively (P<0.05 or P<0.01), and pH value was significant correlated with HS, HA-C, FA-C, Hu-C, SOC, AN and AP negatively (P<0.05). The results showed that, the HS content in NG was lower and its soil quality was poorer. In inverse, the HS content in TG and FG was higher and its soil quality was better. Thus, we recommended develop NG into TG and FG to increase soil fertility.

Key words: Humic substance(HS), Humic acid carbon(HA-C), Fulvic acid carbon(FA-C), Humin carbon(Hu-C), Land use type

摘要： 以衡阳紫色土的天然草地（Natural grassland，NG）、人工草地（Tame grassland，TG）、灌草地（Frutex and grassland，FG）、灌丛地（Frutex，FX）和乔灌地（Arbor and frutex，AF）5种土地利用方式的土壤为研究对象，分析5种土地利用方式土壤的腐殖物质（Humic substance，HS）组成和性质，并探讨与土壤理化性质之间的关系。研究发现：FG的腐殖物质含量最高，其次为TG，NG最低；土壤腐殖物质总碳（Total carbon，T-C）以胡敏素碳（Humin carbon，Hu-C）含量最高，胡敏酸碳（Humic acid carbon，HA-C）含量最低；TG与FG的胡敏酸碳/富里酸碳[Humic acid carbon/Fulvic acid carbon，（HA-C）/（FA-C）]含量最高，NG最低，TG，FG，FX与AF 0~20 cm土层的（HA-C）/（FA-C）含量显著高于20~40 cm土层（P<0.05）；5种土地利用方式的HS，HA-C，富里酸碳，Hu-C，土壤有机碳（Soil organic carbon，SOC），碱解氮（Alkali-hydrolyzable nitrogen，AN）与速效磷（Available phosphorus，AP）两两间呈显著或极显著正相关关系（P<0.05或P<0.01），土壤pH值与HS，HA-C，FA-C，Hu-C，SOC，AN，AP呈显著负相关关系（P<0.05）。研究结果表明，NG的HS组分含量较低，土质较差，而TG，FG的HS含量较高，土质较好，建议将NG开发成TG与FG土地利用方式，以提高土壤肥力。

关键词: 腐殖物质, 胡敏酸碳, 富里酸碳, 胡敏素碳, 土地利用方式