Long-Term Phosphorus Desorption Using Dialysis Membrane Tubes Filled with Iron Hydroxide and its Effect on Phosphorus Pools

Many agricultural fields that have received long-term applications of phosphorus (P) often contain levels of P exceeding those required for optimal crop production. Knowledge of the effect of the P remaining in the soil (residual effect) is of great importance for fertilization management. Plant P availability of residual P in soils is usually estimated using successive cropping experiments carried out in field or greenhouse studies. As this approach is very expensive and time consuming, more rapid soil test methods that can approximate this biological measure are required. The objective of this paper was to use a different approach to evaluate P availability (desorption) over a long period of time instead of the classical means of extraction. Thus, a modified sequential P extraction procedure using dialysis membrane tube filled with ferric hydrate solution (DMT-HFO) was used on the long-term P fertilized soils that received differential P treatments (PoLo, P1L1 and P2L1) to determine the changes...