This document establishes a method for the determination of monosilicic acid concentrations in nonliquid fertilizer materials. Monosilicic acid is reported as silicon (Si).

This extraction method is applicable to the detection of monosilicic acid in nonliquid fertilizer products, blended products, and beneficial substances at silicon (Si) concentrations of 2 to 84 g/kg, with a limit of detection (LOD) of 0,6 g/kg Si, and a limit of quantification (LOQ) of 2 g/kg correlating well with plant uptake.

This method is not applicable to liquid silicon fertilizer sources due to an expected low bias of Si recovery and low correlation with plant uptake.