In Situ Soil Phosphorus Monitoring Probe Compared with Conventional Extraction Procedures

Abstract

In this work, selective chemical sensors of phosphorus (PO₄ ³⁻) installed in PVC probes and their associated instrumentation were evaluated in soil solution phosphorous monitoring. The evaluation was carried out with the addition of a 0.1 mol L⁻¹ P‐PO₄ ³⁻ solution in the soil, followed by data acquisition supplied by the probes; by collecting soil samples in the region where the probes were installed; and by phosphorus determination through conventional laboratory techniques. The phosphorus amounts were determined by spectrophotometry after the following extraction methodologies: Mehlich 1, Mehlich 3, and ionic exchange resin. The results, compared with the potentials registered by the probes, express the best correlation with the results obtained with the resin method. The results indicate good response of the sensors and the potential applicability of these probes to assist in the monitoring of soil nutrients, helping to establish rational processes in the use of fertilizers in crops.

Keywords:

• In situ soil analysis
• phosphorus
• potentiometric sensor
• precision agriculture
• soil monitoring

ACKNOWLEDGMENTS

We are grateful for the financial support provided by the Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP), Coordenação de Aperfeiçoamento de Pessoal de Nível Superior and Direção Geral de Universidades da Espanha do Ministério da Educação, Cultura e Desportos (CAPES/MECD), and Ajuts per a la mobilitat interregional d'investigadors (AIRE) 2002/2003, from the Generalitat de Catalunya (Barcelona, Spain).