Determination of volume weight and water content of wood fiber substrates with different methods

Different methods for the investigation of physical properties of wood fibe r substrates and one other organic substrate were compared. The parameters volume weight and volumetric water content are discussed. The results lead to important aspects for the application of these methods to investigate wo od fiber and other organic substrates. With less work and less time involve d the LUFA method provides similar results as the ISHS method for the deter mination of the volume weight of organic substrates. To evaluate the true c onditions within a pot only the "pot-method" is suitable. An example for ca lculating the N-min-content of the substrate with volume weight obtained fr om different methods is given. To measure the volumetric water content on the base of a given volume weigh t either a modified ISHS method, the positive or the negative pressure meth od can be used. Close relationships have been obtained between the modified ISHS method and the other two methods at pF = 1.0, 1.7 and 2.0. A prerequi site for good results in measurements of substrate mixtures is a homogeneou s material. Thus, independent of laboratory facilities investigation on sub strates can be done at least for physical properties, where the ISHS method has not been introduced.