National Natural Science Foundation of China（No.41671216）and the National Science and Technology Basic Work
[Objective] Clay content and soil color are the most basic physical properties of soil. And soil color, including its hue, value and chroma, is highly influenced by type, content and state of the ferric oxides in the soil. As a result of the intense erosion during the later period of the development of the Loess Plateau, the ancient red clay layer, originally buried down in the lower part of the plateau has emerged up close to or even out of the surface, which is of high significance in the researches on soil genesis and ancient environment. But so far little has been reported about any systematic studies on relationships of soil color with clay content and iron oxides in the ancient red clay soil of the Loess Plateau. The purpose of this paper is to provide certain scientific basis for further studies of soil classification, paleosol and paleoenvironment in the plateau.[Method] Soil samples were collected from the thirty one argillic horizons of the Alfisol profiles in Shanxi Province on the Loess Plateau for analysis of contents of total iron, free iron oxide, amorphous iron oxide and clay and soil color, and further for quantitative exploration of relationships of soil color (hue, value and chroma) with the first three indices, respectively.[Result] Results show that clay content in the argillic horizons was positively related to the content of iron oxides (P<0.01), and so was soil color, and especially soil redness (P<0.01), of which free iron oxide contributed the most. The other soil color parameters, like hue, brightness and chroma, were also significantly related to total iron oxides and free iron oxides, which indirectly indicates that clay content had a certain relationship with soil color. It was also found in field observations that the surfaces of some argic horizons were redder than the matrix inside the horizons, which demonstrates that iron oxide migrates with clay through soil pores and accumulates on the surface.[Conclusion] In Alfisols of the Loess Plateau, the reddish argillic horizons develop mainly from the Tertiary red soil of the Baode series and the Quaternary red clay that outcrop or lie close underneath the surface as a result of intense soil erosion. Their contents of clay and color indicate that the paleoclimate was hotter and wetter in the Tertiary than in the Quaternary in the Loess Plateau region.
张蕾,张凤荣,靳东升,李超.黄土高原淋溶土黏粒、氧化铁与颜色的关系及发生学解释——以山西土系调查的31个黏化层为例[J].土壤学报,2021,58(4):876-886. DOI:10.11766/trxb202001190693 ZHANG Lei, ZHANG Fengrong, JIN Dongsheng, LI Chao. The Correlation of Soil Color Relative to Clay and Iron Oxides in Alfisol of the Loess Plateau and Its Genetic Explanation—A Case Study of the 31 Argillic Horizons Covered in the Soil Series Survey of Shanxi Province[J]. Acta Pedologica Sinica,2021,58(4):876-886.复制