Potential terrain controls on soil color, texture contrast and grain-size deposition for the original catena landscape in Uganda

• Published in: Geoderma 2004-09, Vol.122 (1), p.51-72
• Main Authors: Brown, David J., Clayton, Murray K., McSweeney, Kevin
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; Dambo; Digital terrain modeling; Earth sciences; Earth, ocean, space; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; GLS regression; Soils; Soil–landscape modeling; Spatial statistics; Surficial geology; Texture contrast
• ISSN: 0016-7061; 1872-6259
• DOI: 10.1016/j.geoderma.2003.12.004

Inspired by the catena concept, we returned to the landscape of origin for this idea in central Uganda and applied quantitative soil–landscape-modeling techniques to the study of soil formation. In particular, we employed Generalized Least Squares (GLS) regression to identify potential terrain (and other) controls on surface texture with the goal of explaining texture contrast formation for well-drained red soils, and fluvial deposition for yellow–gray lowland soils. Well-drained red soils and poorly drained yellow–gray soils were identified using a high-resolution spectroradiometer and soil redness was highly correlated with a measure of elevation above the valley floor. For the yellow–gray soils, sand content and sand grain size increased with greater slope gradient and in converging areas—evidence supporting fluvial control of surface soil composition. For red soils, texture contrast increased on lower backslopes, decreased over ferricrete-rich parent material, and had no significant association with either infiltration- or runoff-influenced locations. Surprisingly, texture contrast was also reduced or even inverted on fine scale convexities (