Advertisement

Journal of Mountain Science

, Volume 6, Issue 2, pp 189–196 | Cite as

Micromorphology of surface crusts in the Knersvlakte, South Africa

  • Sarah-Jane C. Fox
  • Anthony J. Mills
  • Rosa M. Poch
Article

Abstract

Soils in the Knersvlakte are particularly prone to crusting and have lower inherent infiltrability than other soils across western southern Africa. Micromorphological techniques were used to examine the structure and porosity of soil crusts in the Knersvlakte to ascertain why crusting is so intense in this region. Quantile regression using boundary lines was employed to examine the relationships between infiltrability and soil properties for all samples (n = 67). This analysis showed that infiltrability is potentially maximal at low waterdispersible ‘clay plus silt’ content and low silt content (r2 = 0.72 and 0.64; respectively, n = 67) (Figure 2). The strength of crusts, pH, EC, clay mineralogy, and water-dispersible clay, silt and ‘clay plus silt’ content were compared, and a pore analysis using optical microscopy was undertaken on images of six soil thin sections (n = 6) (circular and parallel polarizers). Pore analysis was further undertaken on five horizontal slices of equal dimensions taken through each soil thin section. The porosity samples with low infiltrability (< 100 mm·hr−1, n = 4) had greater crust strength, lower porosity (both total and in the least porous slice) and greater water-dispersible ‘clay plus silt’ and silt content than the porosity samples with high infiltrability (/s> 100 mm·hr−1, n = 2). The porosity samples with low infiltrability showed a trend of lower pH and greater water dispersible clay percentage. Porosity varied within the porosity samples due to the presence of dense clay/silt bands (< 0.5 mm in width) with relatively few air vesicles. The porosity samples with horizontal slices of low porosity (but large numbers of air vesicles) had low infiltrability, while those without slices of low porosity (and relatively few air vesicles) had high infiltrability. We conclude that the intense crusting and resultant low infiltrability of soils in the Knersvlakte appears to be related to the formation of thin, dense clay/silt bands in the pedoderm.

Key words

Infiltrability optical microscopy porosity air vesicles 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Agassi, M., Shainberg, I., Morin, J. 1981. Effect of Electrolyte Concentration and Soil Sodicity on Infiltration Rate and Crust Formation. Soil Science Society of America Journal 45: 848–851.Google Scholar
  2. Ankeny, M.D., Kasper, T.C., Horton, R. 1990. Characterisation of Tillage and Traffic Effects on Unconfined Infiltration Measurements. Soil Science Society of America Journal 54: 837–840.Google Scholar
  3. Bailey, S.W. 1980. Summary of Recommendation of AIPEA Nomenclature Committee. Clays and Clay Minerals 28, 73–78.CrossRefGoogle Scholar
  4. Belnap, J., Budel, B., Lange, O.L. 2001. Biological Soil Crusts: Characteristics and Distribution. In: Belnap, J., Lange, O.L. (eds.), Biological Soil Crusts: Structure, Function, and Management., Berlin: Springer.Google Scholar
  5. Bouma, J., Jongerius, A., Boersma, O., Schoonderbeek, D. 1977. The Function of Different Types of Macropores During Saturated Flow Through Four Swelling Horizons. Soil Science Society of America Journal 41: 945–950.Google Scholar
  6. Bresson, L.M., Boiffin, J. 1991. Morphological Characterisation of Soil Crust Development Stages on an Experimental Field. Geoderma 47: 301–325.CrossRefGoogle Scholar
  7. Bresson, L.M., Valentin, C. 1994. Soil Surface Crust Formation: Contribution of Micromorphology. In: Ringrose-Voase, A.J., Humphreys, G.S. (eds.), Soil Micromorphology: Studies in Management and Genesis, Elsevier, Amsterdam.Google Scholar
  8. Casenave, A., Valentin, C. 1989. Les Etats de Surface de la Zone Sahelienne. Influence sur l’infiltration. Paris: ORSTAM, Collection Didactiques.Google Scholar
  9. Evans, D.D., Buol, S.W. 1968. Micromorphological Study of Soil Crusts. Soil Science Society of America Proceedings 32: 19–22.Google Scholar
  10. Fox, D.M., Bryan, R.B., Fox, C.A. 2003. Changes in Pore Characteristics with Depth for Structural Crusts. Geoderma 120: 109–120.CrossRefGoogle Scholar
  11. Frenkel, H., Levy, G.J., Fey, M.V. 1992. Clay Dispersion and Hydraulic Conductivity of Clay-sand Mixtures as Affected by the Addition of Various Anions. Clays and Clay Minerals 40: 515–521.CrossRefGoogle Scholar
  12. Jongerius, A., Schoonderbeek, D., Jager, A., Kowalinskin, S. 1972. Electro-optical Soil Porosity Investigation by Means of Quantimet-B equipment. Geoderma 121: 45–64.Google Scholar
  13. Kapur, J., Ryan, J., Akca, E., Celik, I., Pagliai, M., Tulun, Y. 2007. Influence of Mediterranean Cereal-based Rotations on Soil Micromorphological Characteristics. Geoderma 142:, 318–324.CrossRefGoogle Scholar
  14. Letey, J. 1991. The Study of Soil Structure-science or Art. Australian Journal of Soil Research 29: 699–707.CrossRefGoogle Scholar
  15. Mills, A.J., Fey, M.V. 2004a. Frequent Fires Intensify Soil Crusting: Physico-chemical Feedback in the Pedoderm of Long-term Burn Experiments in South Africa. Geoderma 121: 45–64.CrossRefGoogle Scholar
  16. Mills, A.J., Fey, M.V. 2004b. A Simple Laboratory Method for Measuring the Tendency of Soils to Crust. Soil Use and Management 20: 8–12.CrossRefGoogle Scholar
  17. Mills, A.J., Fey, M.V., Grongroft, A., Petersen, A., Medinski, T.V. 2006. Unravelling the Effects of Soil Properties on Water Infiltration: Segmented Quantile Regression on a Large Data Set from Arid South-west Africa. Australian Journal of Soil Research. (In press)Google Scholar
  18. Moss, A.J. 1991. Rain-impact Soil Crust. I. Formation on a Granite-derived Soil. Australian Journal of Soil Research 29:271–289.CrossRefGoogle Scholar
  19. Murphy, C.P. 1986. Thin Section Preparation of Soils and Sediments. Berkamsted, U.K.: A.B. Academic Publishers.Google Scholar
  20. Norton, L.D. 1987. Micromorphological Study of Surface Seals Developed under Simulated Rainfall. Geoderma 40:127–140.CrossRefGoogle Scholar
  21. Novich, B.E., Martin, R.T. 1983. Solvation Methods for Expandable Layers. Clays and Clay Minerals 32:235–238.CrossRefGoogle Scholar
  22. Pagliai, M., La Marca, M., Lucamante, G. 1983. Micromorphometric and Micromorphological Investigations of a Clay Loam Soil in Viticulture under Zero and Conventional Tillage. Journal of Soil Science 34:391–403.CrossRefGoogle Scholar
  23. Patel, M.S., Singh, N.T. 1981. Changes in Bulk Density and Water Intake Rate of a Coarse Textured Soil in Relation to Different Levels of Compaction. Journal of Indian Society of Soil Science 29:110–112.Google Scholar
  24. Rasband, W.S. 1997–2008. ImageJ. In: U.S. National Institutes of Health, Bethesda, Maryland, USA.Google Scholar
  25. Rhoades, J.D. 1982. Soluble Salts. In: Page, A.L., Miller, R.H., Keeney, D.R. (eds.), Methods of Soil Analysis. Part 2. Chemical and Microbiological Properties., Madison, Wisconsin: Soil Science Society of America, Inc.Google Scholar
  26. Schmiedel, U., Jurgens, N. 2005. Biodiversit Observatories. A new standardised monitoring tool for biodiversity studies. Basic and Applied Dryland Research 1:87–91.Google Scholar
  27. Schoonderbeek, D., Thiel, F., Bisdom, E.B.A. 1983. Quantimet 720 Analysis of Porosities in Back Scattered Electron Scanning Images with Different Phototechniques. Geoderma 30:271–275.CrossRefGoogle Scholar
  28. Shainberg, I., Singer, M.J. 1985. Effect of Electrolytic Concentration on the Hydraulic Properties of Depositional Crust. Soil Science Society of America Journal 49:1260–1263.CrossRefGoogle Scholar
  29. Stoops, G. 2003. Guidelines for Analysis and Description of Soil and Regolith Thin Sections. Madison: Soil Science Society of America.Google Scholar
  30. Tackett, J.L., Pearson, R.W. 1965. Some Characteristics of Soil Crusts Formed by Simulated Rainfall. Soil Science 99:407–413.CrossRefGoogle Scholar
  31. Tisdall, J.M., Adem, H.H. 1986. Effect of Water Content of Soil Tillage on Size-distribution of Aggregates and Infiltration. Australian Journal of Experimental Agriculture 26:193–195.CrossRefGoogle Scholar
  32. Uson, A., Poch, R.M. 2000. Effects of Tillage and Management Practices on Soil Crust Morphology under a Mediterranean Environment. Soil and Tillage Research 54:191–196.CrossRefGoogle Scholar
  33. Valentin, C. 1991. Surface crusting in two alluvial soils of northern Niger. Geoderma 48:201–222.CrossRefGoogle Scholar
  34. Valentin, C., Bresson, L.M. 1992. Morphology, Genesis and Classification of Surface Crusts in Loamy and Sandy Soils. Geoderma 55:225–245.CrossRefGoogle Scholar

Copyright information

© Science Press, Institute of Mountain Hazards and Environment, CAS and Springer-Verlag GmbH 2009

Authors and Affiliations

  • Sarah-Jane C. Fox
    • 1
  • Anthony J. Mills
    • 1
  • Rosa M. Poch
    • 2
  1. 1.Department of Soil ScienceStellenbosch UniversityStellenboschSouth Africa
  2. 2.Department of Environment and Soil ScienceUniversity of LleidaLleidaSpain

Personalised recommendations