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Science et changements planétaires / Sécheresse. Volume 5, Number 3, 173-84, Septembre 1994, Synthèse

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Author(s) : Pierre Rognon

Summary : Climatic dryness (dry seasons, abnormal dry spells or drought) affects the soil directly (rarefaction of water) or indirectly (aeration, salinisation, etc.). Its main consequences on the soil-forming processes are the appreciable changes in chemical processes (and lesser availability of nutrients needed for the plant growth) and the reduction in soil water circulation (and precipitation of dissolved elements: concretions, indurated layers and salinisation). The proportion of organic matter also decreases more and more. In dry-regions pedogenesis, however, the soil’s physical properties become increasingly important: dryness is often associated with a decrease in porosity and other serious changes to the soil structure: great decrease in shrinkage/swelling properties (solidified setting), powdery structure, etc. Changes such as these make water and wind erosion even more damaging, especially when the effect of dryness is reinforced by soil degradation due to man.

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