Retention of phosphate by peat samples

Authors

• Armi Kaila University of Helsinki, Department of Agricultural Chemistry

DOI: https://doi.org/10.23986/afsci.71488

Abstract

The factors on which the retention of phosphorus by peat depends were studied on the basis of a material of 134 virgin peat samples. The coefficient k in the Freundlich adsorption isotherm y = kcn was used as an indicator of the phosphate sorption. The association of k with the sampling depth, the degree of decomposition, weight of volume, pH, extractable calcium, and the iron and aluminum dissolved by 0.1 N hydrochloric acid was treated. The acid-soluble aluminum gave with k a highly significant correlation which did not decrease when the effects of acid-soluble iron and the degree of humification were eliminated. The correlation between k and the acid-soluble iron was also highly significant although less close than the former association, and it was to some extent lowered by the elimination of the effect of aluminum. The fairly low, although statistically significant correlation between k and the degree of humification as expressed by the degree of decomposition or by the volume weight disappeared when the effect of aluminum was isolated. In the present material the sampling depth, pH and the content of extractable calcium did not give any significant correlation with k. As far as these results are valid under natural conditions, aluminum appears to play a more important role in the phosphorus sorption of peat soils than iron does.