Principles and requirements for the soil texture analysis according to methods recommended by International Standard Organization [ISO]

For several years now the Polish Normalisation Committee (PKN) has been angaged in the process of introduction (and implementation) of international standards complying with the Internationsl Standard Organsation (ISO) into the set of of Polish Standards.At present, in the PKN Commission of Soil Physics, a number of such standards are being prepared (translated) -including a very comprehensive standard dealing with partiele size distribution determination in soil material-ISO 11277 [6], Some principles and requirements included in this standard differ significantly from those commonly accepted and widely in use now in numerous pedologie laboratories in Poland [7,8]. Below there are some of the most important differences: (1 ) the requirement to remove organic matter from test samples (using 30% v/v solution of H2O2), (2) the requirement to remove water soluble salts and gypsum (to electrical conductivity 0,4 dS/m), (3) sample dispersion process must be longer than 18 hours. Many other requirements, of relatively lesser importance, in many cases also do not correlate with those commonly accepted in our laboratories.