CHEMICAL-ANALYSIS OF PEATY GROWING MEDIA BY MEANS OF WATER EXTRACTION

In a study with fifty peaty growing media some water extracts were tes ted on their ability to estimate the chemical composition of the ''soi l'' solution. The chemical and physical characteristics of the growing media differed widely. The soil solution was prepared by pressing out 30-50% of the the water from the growing media exactly brought on a w ater content equal to the water content at a pressure head value of -1 .0 kPa. The water extracts compared were, the press extract of growing media brought by a quick method on a water content at a pressure head of -1.0 kPa and an extract prepared from a 1:1.5 (v/v water/growing m edium) suspension. In the extracts all the likely anions and cations w ere determined. The correlation coefficients for the relationships bet ween the analytical data of the soil solution and the analytical data of the extracts varied between 0.975 and 0.993 for the extract prepare d from the media quickly brought to a water content at a pressure head of -1.0 kPa and between 0.912 and 0.992 for the extract prepared from a 1:1.5 suspension. So both extracts are a suitable aid to estimate t he chemical composition of the soil solution. The extraction methods c ompared are discussed on their stability for routine soil testing purp oses. An overall view for the interpretation of the analytical data is presented.