The rapid detection of bioavailable micronutrients Cu/Fe/Zn/Mn in soil using laser-induced breakdown spectroscopy combined with solid–liquid–solid transformation

Abstract

Bioavailable fractions of micronutrients—including copper (Cu), iron (Fe), zinc (Zn), and manganese (Mn)—which comprise only 1–20% of the total soil micronutrient content—are the primary forms accessible for plant absorption and physiological processes. Accurate and timely quantification of these fractions is vital for site-specific nutrient management in precision agriculture. This study presents a novel analytical method that combines laser-induced breakdown spectroscopy (LIBS) with a solid–liquid–solid transformation (SLST) protocol to address conventional detection technique limitations. This integrated method facilitates rapid, in situ, and highly sensitive detection of bioavailable micronutrients (Cu, Fe, Zn, Mn) in complex soil matrices. The results demonstrated that bioavailable micronutrients could be accurately and efficiently detected using the proposed method. The limits of detection (LoDs) for Cu, Fe, Zn and Mn were determined to be 0.06, 0.20, 0.98, and 0.71 mg kg⁻¹, respectively, meeting the classification standards of I–III categories in the classification of bioavailable elements in Chinese soil. Furthermore, the total detection time was reduced to less than 20 minutes, highlighting the method's efficiency for rapid soil assessment. This analytical approach offers a practical and innovative solution for real-time monitoring of soil nutrients, facilitating data-driven fertilization strategies for precision agriculture.