Role of a cyanobacterial cover on structural stability of sandy soils in the Sahelian part of western Niger
In: ISSN: 0016-7061, 2001
Online
academicJournal
Zugriff:
Microbiotic soil crusts, mostly formed by cyanobacteria, are widespread on the surface of fallow land in western Niger. They lie adjacent to completely bare soils. We have investigated the structural stability of these soils by testing aggregate breakdown under fast-wetting, slow-wetting and mechanical breakdown. The tests were effected on aggregates ranging from 3 to 5 mm in size. These experiments were completed by micromorphological examinations under light and scanning electron microscope. For all tests, the fragment size distribution and the mean weight diameter (MWD) revealed the great stability of aggregates from soils with a cyanobacterial cover (MWD 1.82 to 3.10 mm), compared to those from soils devoid of cyanobacterial cover (MWD 0.25 to 1.26 mm). Fast- and slow-wetting of microbiotic soil crust material induced a lesser disaggregation of aggregates compared to mechanical breakdown. On the contrary, fast-wetting and mechanical breakdown of aggregates from soils devoid of cyanobacterial cover induced a greater disaggregation than slow-wetting. Microscopic examination of microbiotic crusts revealed an intricate network of filamentous cyanobacteria and extracellular polymer secretions, which binds and entraps mineral particles on the soil surface. Organo-mineral aggregates ranging from 0.10 to 0.12 mm were observed. Below the superficial crusts, filaments and residual organic matter bind tightly soil particles, thus giving a compact structure. The great stability of aggregates of soil with cyanobacterial cover is likely related to the binding and gluing effect of cyanobacteria and derived organic matter. This is consistent with the positive correlation between MWD values and organic carbon content. The present results thereby confirm the resistance to erosion of soil with microbial cover as indicated by field measurements.
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Role of a cyanobacterial cover on structural stability of sandy soils in the Sahelian part of western Niger
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Autor/in / Beteiligte Person: | Malam Issa, Oumarou ; Le Bissonais, Yves ; Défarge, Christian ; Trichet, Jean ; Groupe d'Étude sur les Géomatériaux et Environnements Naturels, Anthropiques et Archéologiques - EA 3795 (GEGENAA) ; Université de Reims Champagne-Ardenne (URCA)-SFR Condorcet ; Université de Reims Champagne-Ardenne (URCA)-Centre National de la Recherche Scientifique (CNRS)-Université de Reims Champagne-Ardenne (URCA)-Centre National de la Recherche Scientifique (CNRS)-Maison des Sciences Humaines de Champagne-Ardenne (MSH-URCA) ; Université de Reims Champagne-Ardenne (URCA)-Université de Reims Champagne-Ardenne (URCA) ; Unité de Science du Sol ; Institut National de la Recherche Agronomique (INRA) ; Institut des Sciences de la Terre d'Orléans (ISTO) ; Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS) |
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Zeitschrift: | ISSN: 0016-7061, 2001 |
Veröffentlichung: | HAL CCSD ; Elsevier, 2001 |
Medientyp: | academicJournal |
DOI: | 10.1016/S0016-7061(00)00093-8 |
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