Abstract
The effect of topsoil reduction on yields of cereals on soils developed from loess was evaluated on the basis of a case study and analysis of regional data. Differentiation of yields depended on climatic conditions, soil erosion class and its location in the landscape. The results showed a tendency towards soil productivity decrease with topsoil losses. The greatest decreases were found on severely eroded (18 per cent), for the case study and on very severely eroded soil developed from calcareous loess (25 per cent), for the regional database. On average, yields decreased by 3โ4ยท3 per cent per 10โcm of topsoil reduction. The yield decrease on eroded soils was partly compensated by its increase in some areas of colluvials. Average changes of productivity were compiled together with percentage share of various soils in four loess catchments. The sites were characterised by various time of agricultural land use, start of tractor tillage and percentage of soils transformed by erosion. Despite the differences, similar levels of decrease of cereals productivity, in the range of 5โ7 per cent, were found for all the sites at catchment scale. Copyright ยฉ 2010 John Wiley & Sons, Ltd.