A Modified DMT-HFO Technique for Investigating the Kinetics of Phosphorus Desorption from Calcareous Soils and its Relationship with Maize Growth

In this research, phosphorus (P) desorption was investigated using DMT-HFO as an “infinite” sink for 10 calcareous soils over a period of 1–35 days and the kinetic data was related to soil properties and P uptake by maize (Zea mays L.). First- and second-order, and simple Elovich equations adequately described P desorption kinetics, however parabolic, exponential and zero order equations provided the best fits to the data. A systematic relationship exists between the second order rate parameter (k₂) and the clay content of the soils. There are positive relationships between P desorption rate constants (for zero order, Elovich and parabolic equations), and both dry matter and P content of maize shoots and also for roots. These relationships indicate that P desorption rate may be a limiting factor for maize growth in these soils. The DMT-HFO technique may be used to assess the long-term availability of P to plants.