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

Abstract

Different methods for the investigation of physical properties of wood fiber 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 wood fiber and other organic substrates. With less work and less time involved the LUFA method provides similar results as the ISHS method for the determination of the volume weight of organic substrates. To evaluate the true conditions within a pot only the,,pot-method is suitable. An example for calculating the N min -content of the substrate with volume weight obtained from different methods is given. To measure the volumetric water content on the base of a given volume weight either a modified ISHS method, the positive or the negative pressure method 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 prerequisite for good results in measurements of substrate mixtures is a homogeneous material. Thus, independent of laboratory facilities investigation on substrates can be done at least for physical properties, where the ISHS method has not been introduced.