De bodemgesteldheid van de IJpolders en een onderzoek naar het verband tussen de bodem en de suikerbietenopbrengst in de Haarlemmermeer en de IJpolders in het jaar 1949

A soil survey in the Y-polders was combined with studies of yield of sugarbeet on different soils. Subsoil differences were shown to be the most important factor. Topsoils in the Y-polders proved to be uniform in composition and to consists of young Ysselmere clay (underwater deposits) with a lutum (clay) content of 35-40%. The thickness of the clay layer proved to be very varied. Sands, peat, peat detritus, peaty silt were the materials of which the subsoil was built up through an intricate history of sedimentation. Therefore soils were classified on clay thickness and subsoil characteristics.To test the agricultural value of this classification, yields of various soil types were compared in the polders and on some soils of the Haarlemmermeer. This data proved that high humus contents caused low contents of sugar. The influence of decalcified topsoils and cat-clay subsoils was not important in 1949 because of the weather. Coarse sandy subsoils and heavy layers had much influence; maximum yields were achieved on soils with 75 cm Y clay. A suitability scheme for sugar- beets was derived from the data.