COPPER BIOAVAILABILITY IN CALCAREOUS SOIL SAMPLES .2. RELATION TO THECHEMICAL FRACTIONATION OF COPPER

The bioavailability of copper is usually measured by chemical reagents such as EDTA. However, evidence of cupric deficiency for plants may b e observed without the chemical test for it. Thus, the aim of this stu dy was to apply classical sequential extraction procedures, used in en vironmental studies, in order to obtain a chemical fractionation of co pper and to examine the possible relations between these fractions and the bioavailability of copper. The study was performed on calcareous soil samples collected in Eastern France and corresponding to an agron omical assay to study copper deficiency. The results of the copper fra ctionation were described in a first paper. In this paper, the possibl e relations between copper fractionation and grain yields obtained in the plots of the agronomical assay will be discussed. From a statistic al point of view, there was no significant correlation between the cop per fractions and yields, but significant relations between sampling y ear or sampling location and yields are observed. As a conclusion, a c hemical fractionation of copper does not seem appropriate in order to predict its bioavailability.