TESTING A METHOD FOR ESTIMATING WATER-RETENTION PARAMETERS USING THE LABORATORY DATABASE OF THE LOWER SAXONY SOIL INFORMATION-SYSTEM

The validity of the method used for estimating field capacity (pF > 1.8), plant available water (pF 1.8 - 4.2), air capacity (pF < 1.8), and total pore volume from soil texture, packing density (bulk density + 0.009 % clay) and humus content described by the Arbeitsgruppe Bodenkunde (1982) was checked on the basis of 1693 pF curves of the laboratory database of the Lower Saxony Soil Information System (NIBIS). The positive and negative corrections for humus content applied in this method to the above parameters are clearly too small. Use of tables for estimating the pore volume of humus-free soils leads to overestimation. It will only be possible to work out an alternative method applicable to all classes of soils when the database has been extended.