Evaluation of phosphorus availability in soil by LIBS spectroscopy

• Grant number: 25/04662-5
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: June 01, 2025
• End date: January 31, 2026
• Field of knowledge: Physical Sciences and Mathematics - Chemistry - Analytical Chemistry
• Principal Investigator: Edilene Cristina Ferreira
• Grantee: Guilherme Caliani Mathias Netto
• Host Institution: Instituto de Química (IQ). Universidade Estadual Paulista (UNESP). Campus de Araraquara. Araraquara , SP, Brazil
• Associated research grant: 23/08034-3 - Agriculture 4.0: Development of a new technology for phosphorus speciation in soils, AP.R

Abstract

Population growth and the increasing demand for food make sustainable agriculture increasingly essential. In this context, optimizing the efficiency and sustainability of agricultural practices requires an in-depth understanding of soil properties, particularly phosphorus (P) content, a vital macronutrient for plants. Although present in large quantities in the soil, most P exists in non-labile forms, unavailable for root absorption, necessitating the continuous reapplication of phosphate fertilizers. The available fraction (labile P) is limited and can become unavailable due to the presence of Al, Fe, and Ca, which promote its fixation into forms that are not readily accessible to plants. This study proposes the use of laser-induced breakdown spectroscopy (LIBS) to assess the correlations between the spectral signals of Al, Fe, and Ca and those of P. LIBS stands out for its rapid analysis, minimal sample preparation, and absence of chemical reagents, making it a promising alternative for evaluating P availability in soil. The primary objective is to identify the P spectral lines (atomic, ionic, or molecular) that are most strongly correlated with its non-labile fraction and to assess factors, such as soil pH, that influence its availability. The findings will contribute to improving phosphorus fertilization management strategies, enabling more precise fertilizer application recommendations, reducing costs, and mitigating environmental impacts such as water eutrophication. Furthermore, the application of LIBS could facilitate the development of faster and more accessible P analysis methods for field use.