喀斯特石漠化地区土壤Fe组成及其发生学意义

土壤中氧化铁的组成反映了土壤的成土过程和环境条件。通过对西南喀斯特石漠化地区不同石漠化阶段山地自然土壤和农田土壤Fe组成的分析,研究了土壤全铁、游离氧化铁和非晶形氧化铁的分布规律,探讨了喀斯特地区石漠化土壤的发育过程和Fe的指示作用。研究表明:①喀斯特地区土壤表层全铁含量在38.9～53.9g/kg之间,游离氧化铁含量在18.0～26.7g/kg之间,铁游离度在44.1%～73.4%之间,铁活度在7.2%～11.4%之间。②随着石漠化程度的加剧,土壤游离氧化铁和铁游离度呈增加的趋势,而铁活度呈降低的趋势。③在土体分布上,自然土壤剖面随深度的增加,土壤铁游离度和铁活度呈明显降低的趋势,而农田土壤铁游离度呈增加的趋势。④喀斯特地区的土壤是石灰岩溶蚀风化的产物,人为活动干扰下的自然土壤石漠化过程是在水力作用下的表土侵蚀过程,而农田土壤受水分垂直运动的影响,是土壤丢失的过程。

Characteristics of soil iron and its pedogenetic significance in the process of Karst rocky desertification, southwestern China.

Soil iron oxide indicates soil-forming process and soil-forming environment under which the iron oxide was formed. Soil iron oxides of natural soils and agriculture soils in different phases of Karst rocky desertification in southwestern China were analyzed this time. The distributions of soil total iron (Fet), free iron oxide (Fed) and amorphous iron (Feo) were also studied, and soil-forming process in the Karst rocky desertification regions was discussed. The results were as follows: the soil total iron content in Karst region ranges from 38.9~53.9 g/kg. The free iron oxide content ranges from 18.0~26.7 g/kg. The degree of free iron ranges from 44.1% to 73.4%, and the degree of active iron ranges from 7.2% to 11.4%. With the aggravation of rocky desertification, the free iron oxide content and the free iron degree increase, and the degree of active iron decreases. The degree of free iron and the active iron of different profile in karst natural soils in surface layer is larger than bottom layer, but the degree of free iron in agriculture soil in bottom layer is larger than surface layer. The soil-forming process of karst region is due to limestone corrosion. Under anthropogenic disturbance, the essence of rocky desertification process in natural soils is soil and water erosion process in surface layer, and that in agriculture soils was "soil loss" process which was affected by water vertical migration.