Preliminary ICP OES-based multi-element profiling of soil amended with household organic waste-derived Bokashi

Household organic waste-derived Bokashi may support resource recovery, but its effect on the strong-acid-digestible multi-element profile of soil requires cautious analytical evaluation. This preliminary study compared two homogenized soil conditions: pre-application soil and soil sampled after incorporation and maturation of household waste-derived Bokashi. Eight measurements per condition were analytical subsamples of the corresponding homogenized material and were not independent field replicates. B, Ca, Cd, Cu, Fe, K, Mg, Mn, Pb, and Zn were determined by ICP OES after microwave-assisted digestion with HNO3, HCl, and HF. Analytical performance characteristics included R2 values of 0.999867–0.999953, relative standard deviation (RSD) values of 0.72–1.05%, limit of detections (LODs) of 0.008–0.984 mg kg−1, and limit of quantifications (LOQs) of 0.027–3.280 mg kg−1. In the amended-soil analytical profile, mean concentrations ranged from 0.16 mg kg−1 for Cd to 12,985.96 mg kg−1 for Ca. The largest relative differences from the pre-application profile occurred for Cu (48.65%), Ca (34.61%), and B (27.10%); Fe, K, Mg, Mn, and Zn differed by 4.84-8.30%, while Pb differed by 2.92%. Exploratory principal component analysis (PCA) and hierarchical clustering separated the two analytical profiles, but this separation does not constitute evidence of a replicated treatment effect. The approach provides rapid multi-element screening across major, trace, and potentially toxic elements within one measurement platform. Its interpretation is limited by the absence of independent field replication, certified reference material or recovery testing, separate elemental characterization of the Bokashi batch, and measurements of plant-available fractions.