Contributo dell'argilla e della sostanza organica alla capacità di scambio cationico delle terre brune della Sardegna Nord-Orientale

The contributions of clay and organic matter relative to 24 samples collected from non calcic brown soils of N-W Sardinia - were measured using statistical analyses. Within the limits of the standard errors the regression coefficients of day and organic matter increase linearly with pH. The average contribution to CEC of day decreased from 64% at pH 3 to 300% at pH 8. The clay CEC was 30, 34, 39 meq per 100 g. al pH 3,5 and 8, respectively, while that of the organic matter was 62, 131, 231 meq per 100 g. The high increase of CEC between pH 5 and 8 was interpreted in view of eventual liming of cultivable soils.