Natural Potassium (K) Isotope Fractionation during Corn Growth and Quantification of K Fertilizer Recovery Efficiency Using Stable K Isotope Labeling

Summary

This pot study demonstrates the application of high-precision stable potassium isotope analysis (δ41K) as a tracer method to improve quantification of fertiliser-derived K uptake in corn. Using 41K-labelled fertiliser at three soil application rates, the authors estimated fertiliser recovery efficiency at 59–81% and characterised preferential uptake of lighter K isotopes. The stable isotope approach proved superior to conventional K concentration-based methods, which underestimated utilisation at low K availability and overestimated it at high K availability.

UK applicability

The methodology may be applicable to UK arable systems where improved measurement of potassium fertiliser efficiency is sought, although the findings derive from pot conditions and would require field validation in UK soil and climate contexts. The approach could support more accurate quantification of K cycling in UK soils, though adoption would depend on availability of isotope analysis capacity and cost-effectiveness relative to existing diagnostic methods.

Key measures

δ41K values (K isotope ratios); fertiliser-derived K in corn shoots (estimated via 41K tracer enrichment); K concentration; apparent fertiliser recovery efficiency (%); mass-dependent fractionation factor between shoot and soil (‰)

Outcomes reported

The study quantified potassium fertiliser uptake efficiency in corn using stable K isotope labelling, demonstrating apparent fertiliser recovery efficiency of 59–81% across three soil K treatment levels. The research also characterised mass-dependent K isotope fractionation during plant uptake, showing preferential uptake of light K isotopes by corn shoots.

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