Aggregation of soil particles by iron oxides in various size fractions of soil B horizons
1991
Barberis, E. | Marsan, F.A. | Arduino, E.
Quantitative relationships between aggregation of soil particles and the content of haematite and goethite were studied by removing iron oxides, with dithionite-citrate-bicarbonate (DCB) and oxalate reagents, from various sizes of soil separates which were stable to sodium hexametaphosphate, and then determining the particle-size distribution. Significant quantitative relationships were found between DCB-extractable oxides and particles obtained from the separates up to 20 micrometer, whereas oxalate-extractable oxides were correlated only with < 0.2-micrometer particles. Oxalate-extractable oxides were observed to aggregate a greater quantity of fine clay and a larger surface area of particles per gram of oxide than DCB-extractable oxides. A more efficient mechanism of aggregation was postulated for the oxalate-extractable oxides than for the DCB-extractable oxides. There were fewer aggregated particles in soils containing haematite and goethite than in soils containing only goethite. This was attributed to differences in pedoenvironment, rather than to a difference in the behaviour of the oxides. Although various clay minerals were identified in the soils studied, no preferential aggregation of any mineral was observed.
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