Original Articles

Soil aggregate stability: The contribution of biological and physical processes

Published in: South African Journal of Plant and Soil
Volume 4, issue 3, 1987 , pages: 121–126
DOI: 10.1080/02571862.1987.10634957
Author(s): M.B. MolopeCrop production, Agriculture Department, Private Bag X2039,


The roles of fungal growth, soil organic matter and particle re-orientation in soil aggregate stabilization during ageing of two British soils with different cropping histories were studied. Soils were subjected to simulated cultivation, and the subsequent changes in aggregate stability during ageing assessed by turbidimetry test. An initial increase in aggregate stability was accompanied by prolific fungal growth, which was seen by scanning electron microscope and estimated by means of ergosterol measurement. This increase in stability may be partly explained by the retention of soil particles within the reticulum of fungal hyphae. When all biological activity was prevented by soil sterilization, a residual process remained which still caused some increase in stability of moulded balls of soil. Allowing soils to rest a few days after tillage would therefore impart some resistance to dispersion when exposed to second implement passes or destructive forces associated with raindrop impact.

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