Simplifying Sample Preparation for Soil Fertility Analysis by X-ray Fluorescence Spectrometry

Area of Science:

• Geochemistry
• Soil Science
• Analytical Chemistry

Background:

• Portable X-ray fluorescence (pXRF) offers a practical, eco-friendly alternative to traditional laboratory soil analyses.
• Assessing soil nutrient status is crucial for agriculture and environmental monitoring.

Purpose of the Study:

• To evaluate the performance of pXRF sensors for predicting soil exchangeable nutrients.
• To compare two sample preparation methods: pressed pellets and loose powder.

Main Methods:

• pXRF analysis using a Rh X-ray tube and silicon drift detector.
• Calibration models developed with 58 soil samples using leave-one-out cross-validation.
• Sample homogeneity assessed via X-ray fluorescence microanalysis.

Main Results:

• pXRF accurately predicted exchangeable potassium (ex-K) and calcium (ex-Ca) with R² ≥ 0.76 and RPIQ > 2.5.
• Pressed pellets showed a slight performance advantage over loose powders for ex-K and ex-Ca prediction.
• Satisfactory results were achieved with loose powders, requiring minimal sample preparation.

Conclusions:

• pXRF is a viable tool for predicting soil exchangeable nutrients, particularly ex-K and ex-Ca.
• Loose powder sample preparation offers a practical approach with minimal sample handling.
• Further research is warranted for pXRF application in tropical soil analysis.