Download or read book Factors Affecting Phosphate Sorption by Soils and Minerals written by Sergio Jorge Volkweiss and published by . This book was released on 1973 with total page 316 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objectives of this research were to study the P sorption characteristics of soils and the effects of pH and of cation type and concentration on P sorption by soils and minerals. In an attempt to characterize the nature and properties of P sorption sites of soils, P sorption isotherms in a 0.1 N NaC1 system were obtained for six limed and unlimed agricultural soils from Rio Grande do Sul, Brazil. The equilibration time was 48 hours and the concentration of P in the final solution varied from near zero to 20 ugP/ml. Langmuir plots (c/x vs c) of the data resulted in curvilinear and/or multi-straight line relationships suggesting the presence of 2 or more populations of sites with different affinities for P. An iterative multiple regression analysis computer program that assumes that each population of site follows the Langmuir equation was used to analyze the sorption data. Three populations of sites with different affinities for P were detected and the Langmuir constants, k (binding energy term) and b (sorption maximum) were estimated for each population of sites. The median and range for values of k (ml/ug P) and b (ugP/g) for the three populations of site were in decreasing order of affinity for P:K1 = 140, (40-2870) and b1=120 (8-370); K2=2.4, (0.63-10) and b2=174, (25-704); and K3 =0.095, (0.051-0.27) and b3=763 (131-1460). On the average, the total number of P sorption sites (total) was made up of 10% of sites with high affinity for P, 22% with moderate and 68% with low affinity ...