Phosphorus extractability in surface soil samples as affected by mixing with subsoil

• Main Author: T. PELTOVUORI
• Format: Article
• Language: English
• Published: Scientific Agricultural Society of Finland 2008-12-01
• Series: Agricultural and Food Science
• Online Access: https://journal.fi/afs/article/view/5736

Samples taken from the plow layer (Ap horizon)and subsoil (B horizon)of six cultivated soil profiles were analyzed as original samples and as mixtures containing 25% or 50% material from the B horizon. Acid ammonium acetate extractable phosphorus, degree of phosphorus saturation (DPS), and a phosphorus Q/I-plot were determined for each sample and mixture to evaluate the effect of bulking of dissimilar materials on results and to assess the possibilities of reducing P solubility in P-enriched surface soils. The results obtained for the mixtures were compared with mass-weighed average results of the original samples. Measured values of DPS corresponded well and those of acetate-extractable P reasonably well to the estimated values, and the results were linearly correlated with the mass fraction of horizon B material in the mixed samples (r2>0.85).Water-extractable P behaved dissimilarly; the equilibrium P concentration (EPC) estimated from the Q/I-plots decreased dramatically when the fraction of highly sorptive horizon B material increased in the mixture. The marked effect of subsoil material on EPC values may provide a technique to reduce potential losses of soluble P by deep tillage.;