Crust development in relation to vegetation and agricultural practice on erosion susceptible, dispersive clay soils from central and southern Italy

The propensity for dispersive soils to crust when exposed to rainfall is influenced by vegetation cover and agricultural practice. Crust formation on cambisols developed in dispersive Plio-Pleistocene clays from the Creti Senesi, Tuscany, central Italy and from around Pisticci, Basilicata, southern Italy was investigated in the laboratory using simulated rainfall. No discernable crusts formed on samples of aggregates obtained from beneath woodland or scrub, but those from tilled arable land, from badlands and from former badlands reclaimed for agriculture by modelling the landscape, each developed distinctive crusts. Crust development was inversely related to stability of the soil aggregates which in these soils was most strongly determined by organic matter content and exchangeable sodium percentage. Soil aggregates from reclaimed land used for cereal cultivation remain very vulnerable to the crusting when exposed to rainfall by tillage operations. (C) 2001 Elsevier Science B.V. All rights reserved.