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SUMMARYPlant:soil ratios (CRs) of 85Sr concentration were studied in wheat, lucerne, lettuce, radish, string bean (Phaseolus vulgaris), and cucumber grown in pots in eight Greek soil types in a glasshouse pot experiment in 1989.The CRs of the crops and of the plant parts studied differed according to soil type. They ranged from 0·034–1·39 for wheat grains to 7·6–36·5 for cucumber stems and leaves. The CRs of the edible parts were much lower than those of the other plant material.The correlation between CRs and clay content was negative and, in most cases, significant (P = 0·05–0·01) or highly significant (P < 0·01). The negative correlation improved (higher absolute value of r, lower variability) if clay plus silt content or cation exchange capacity was used instead of clay content.The correlation between CRs and soil properties was greatest for soil pH (r = –0·89) and decreased in the order: pH > total clay plus silt ≃ cation exchange capacity > total clay.

The relationship between values of 85 Sr concentration ratios (CRs) and exchangeable bases, expressed in absolute (mmol/kg) or relative (percentage of cation exchange capacity (CEC)) terms, was considered using the results of a glasshouse pot experiment conducted in 1989, for soils and crops of Greece. Exchangeable calcium, expressed in mmol/kg, presented, in most instances, a significant (P = 005-001) or highly significant (P < 001) negative correlation with the CRs of various crops or plant parts, while exchangeable calcium plus magnesium or total exchangeable bases (expressed also in mmol/kg) showed an even better correlation (higher values of r, lower variability). Expression of the amounts of exchangeable bases in relative terms further improved the correlation coefficient in each comparison. The correlations between the percentage of exchangeable (Ca + Mg) or exchangeable bases and CRs, which were always negative, were significant or highly significant for all tested crops or plant parts. The correlation between CRs and soil properties was greatest for exchangeable (Ca + Mg) expressed as a percentage of CEC (r = -0-92) and followed the order: Exchangeable (Ca + Mg) as % of CEC « exchangeable bases as % of CEC > exchangeable (Ca + Mg) in mmol/kg « exchangeable bases in mmol/kg > exchangeable Ca as % of CEC > exchangeable Ca in mmol/kg.Quantitative relationships between CRs of the tested crops or plant parts and exchangeable calcium plus magnesium (% of CEC) of soils are also presented.

The weathering of the fine sand‐size mica flakes in two soils (I and II) developed in northern Greece under the same climatic, drainage, and age conditions, but under different vegetational cover, was investigated by chemical analysis, X‐rays, differential thermal analysis (DTA), infrared, and Mössbauer spectroscopy. It was found that hydrobiotite was inherited from the consolidated bedrock and underwent further pedogenetic oxidation, vermiculitization and kaolinitization in the soil. The oxidation of Fe seemed to take place preferentially in the larger and more symmetrical octahedral sites of the latice. Kaolinite was formed through transformation of the mica flakes in soil II which is now covered by scotch pine (Pinus sylvestris L.) and Vaccinium, while gibbsite was formed in the flakes of soil I, which has a spruce (Picea excelsa L.) cover. No detectable montmorillonite was found in the flakes examined in this study.Rates of weathering and physical disintegration result in conditions which produce a more weathered appearance of the fine sand‐size flakes in the section of the profiles immediately below the surface in soil II compared to those in soil I.The Mössbauer parameters of the flakes indicate that weathering of biotite to 2:1 minerals results in oxidation of the ferrous ions to ferric in the two octahedral sites of the lattice. Of these two sites the less symmetrical with hydroxyls in cis position is more resistant to oxidation.