Precision of the Anion Exchange Membrane Phosphorus Technique When Using a Range of Low-Ionic Solutions in Analysis of Heterogeneous Mine Soils

Abstract

The anion exchangeable membrane phosphorus (P) method can be used across a range of soils to analyze P for vegetation and has the potential to be applied to heterogeneous mine soils. Enhanced small-scale variability in mine soils can potentially cause enhanced and irregular P fluctuations during extraction, leading to errors in analysis of exchangeable membrane P. Anion exchange membranes in combination with low ionic solutions may be able to reduce this error and improve precision of the measurement. The authors undertake a full inorganic P fractionation to determine if the ionic solutions [deoionized water (DI), 0.01 M calcium chloride (CaCl₂), potassium chloride (KCl), and ammonium fluoride (NH₄F)] change the anion exchangeable membrane–extractable P and in turn the fractionation of P. In addition, the relationship between anion exchangeable membrane P and P-buffering index is analyzed to ascertain the accuracy of the methods. The precision and effect on subsequent P fractions for each extracting reagent was specific to the soil type, most likely related to cations in the soil. Use of NH₄F and DI with anion exchange membranes was a precise method [coefficient of variation (CV) < 20%] for measuring water exchangeable P, with no or minor changes to subsequent fractionations. Calcium chloride (CaCl₂) causes significant changes to P fractionations and resulted in highly variable (CV > 100%) results across all soils.

Keywords:

• Fertility
• mining
• nutrients
• rehabilitation
• small scale
• variation

Acknowledgments

The authors thank Andrew Higgins, Angus Gratton, and Todd Bertwell for laboratory assistance; and Eric Craswell, CSIRO, and the CSSPA reviewers for comments on the manuscript.