Soil structural behaviour in flooded and agricultural soils of the Argentine pampas

摘要: Soils of the Argentine Pampas have been developed over same parent material (loess), but evolved under different topography and land use. This led to soil structural behaviour. In flooding Pampa Argentina soils (Solonetzes) are flooded each winter-spring dried summer, grazed by livestock all year round. Little is known about cattle trampling effects these environmental conditions. nearby rolling Pampa, there silty loams affected physical deterioration water erosion losses after long term conventional tillage (CT). After continuous zero (ZT) often develop shallow compaction. abiotic biotic mechanisms recovery. The general objective this thesis was analyze comparatively natural made-man factors affecting behaviour in with similar (loess) vegetation (grassland), later relief use factors. results showed occurrence significant volume changes swelling shrinking. swell during because a process air entrapment. Livestock causes mechanical destruction surface macropores summer when dries. regeneration damaged pores takes place flooding, at maximum. Droughts -and not floods- cause negative area. macropore volumes were determined pasture, CT ZT situations, showing none effect from management. Topsoil hardening found short ZT. Results greenhouse experiment that aggregate stabilization requires previous fragmentation wetting-drying cycles. Clod shrinkage curves cracking studies do expected poor response W/D However, their filled porosity increases little drying. topsoil aggregation be mainly