Abstract
Two newly introduced extraction techniques for determining total organic P (P0) were compared with the standard high-temperature ignition method in selected savanna soils of Nigeria. The two extraction techniques were: (1) concentrated H2SO4 and dilute base sequential extraction (18 N H2SO4 and 0.5 N NaOH) and (2) basic EDTA method (0.25 M NaOH plus 0.05 M Na2EDTA). The concentrated H2SO4 and dilute base method extracted significantly higher total P0 than the high-temperature ignition method and the basic EDTA extraction. The high-temperature ignition and the basic EDTA extraction gave similar total P0 values (mean=91 mg kg–1 for ignition and 90 mg kg–1 for basic EDTA). The precision of the methods, determined by coefficients of variation (CV, %) associated with each P0 determination method in the soils, was better for the concentrated H2SO4 and dilute base extraction method (CV=13%) than the ignition method (CV=18%) and the basic EDTA method (CV=15%). The high C : P0 ratios determined for the high-temperature ignition and basic EDTA extraction indicated that the two methods underestimated total P0 in the soils. The concentrated H2SO4 and dilute base sequential extraction appears to be suitable for the rapid determination of P0 in savanna soils because the method can be simplified to a single-step analysis.
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Received: 14 November 1997
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Agbenin, J., Iwuafor, E. & Ayuba, B. A critical assessment of methods for determining organic phosphorus in savanna soils. Biol Fertil Soils 28, 177–181 (1999). https://doi.org/10.1007/s003740050481
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DOI: https://doi.org/10.1007/s003740050481