Phosphorus sorption-desorption in alluvial soils of a young weathering sequence at the Danube River

Soil parameters change continuously over time and the duration of pedogenesis may significantly affect a soils' sorption capacity for nutrients and contaminants. In former studies, we showed that progressing pedogenic development had increased the retention capacities for Cu and Cd in young alluvial soils at the Danube River (Austria). The present study was conducted to evaluate the impact of pedogenesis on phosphorus (P) retention in these soils, which represent a weathering sequence covering an age gradient from <20 yr to <500 yr. We performed batch sorption experiments followed by three subsequent desorption steps. Phosphorus retention differed strongly among the studied soils and ranged from 11 to 40% when 1000 mg phosphate - P kg(-1) was added. The subsequent desorption experiments with 0.01 m KCl solution revealed a high mobility (up to 89%) of this recently added P. Correlation analyses showed that P retention in the studied samples was positively correlated to dithionite-extractable Al, Mn and Fe, oxalate-extractable Mn and clay content. The present study revealed that P sorption was not influenced by soil development. The composition of the soil parent material, as affected by differences in sedimentation conditions across the studied floodplain, had a stronger impact on P sorption than the changes induced by 500 yr of pedogenesis under the continental climate of Central Europe. (c) 2008 Elsevier B.V. All rights reserved.