Validation of a phosphovanadomolybdate UV-VIS spectrophotometric method for the determination of plant-available phosphorus in agricultural soils and evaluation of dissolved silicon interference

Reliable determination of plant-available phosphorus is essential for soil fertility evaluation and
sustainable nutrient management. In the present study, a UV–Visible spectrophotometric method based
on the phosphovanadomolybdate reaction was validated for the determination of plant-available
phosphorus in agricultural soils following Egner–Riehm ammonium lactate (AL) extraction. In addition,
the influence of dissolved silicon on the analytical performance of the method was investigated.
Validation included assessment of linearity, sensitivity, selectivity, trueness, accuracy and precision.
Excellent linearity was obtained over the concentration range of 1–20 mg P L⁻ ¹ (R² > 0.999), while the
calculated limits of detection and quantification confirmed adequate sensitivity for routine soil analysis.
The influence of dissolved silicon was negligible, with a calculated matrix effect of only 0.9%, indicating
no significant interference under the selected analytical conditions. Trueness was verified using a BIPEA
certified reference soil material, whereas accuracy was assessed by the standard addition procedure. The
obtained z-score (<2), recoveries (82.1–93.3%) and repeatability (RSD = 0.09–0.67%) confirmed
satisfactory analytical performance. The validated method provides a reliable and robust analytical
approach for routine determination of plant-available phosphorus in agricultural soils.