Soil pH Measurement with Reactive Paper Test Agrociencia Uruguay - Volumen 19 2:68-74 - julio/diciembre 2015 The pH test papers (strips) may be useful for measuring soil pH. The pH values for

  • Andrés Beretta Facultad de Agronomía, Universidad de la República
  • Daniel Bassahun INIA La Estanzuela. Laboratorio de Suelos, Plantas y Aguas. Ruta 50, km 11, 70.000 Colonia, Uruguay
  • Raquel Musselli INIA La Estanzuela. Laboratorio de Suelos, Plantas y Aguas. Ruta 50, km 11, 70.000 Colonia, Uruguay
  • Deborah Torres INIA La Estanzuela. Laboratorio de Suelos, Plantas y Aguas. Ruta 50, km 11, 70.000 Colonia, Uruguay
Keywords: organic carbon, pH, colorimetry, potentiometry

Abstract

The pH test papers (strips) may be useful for measuring soil pH. The pH values for 51 samples were measured. The objective was evaluate the precision and accuracy of these measures. We compared three methods to measure the pH (soil:water 1:2.5): electrode (pH_electrodo); paper test strips either immediately after inmersion (pH_T), or two hours after inmersion (pH_T_RL). Millipore® pH paper strips graduated per unit of pH were used. Electrical conductivity (EC) and soil organic carbon (SOC) were analyzed in each sample. The pH_electrodo values were taken as reference. The pH_T and pH_T_RL values had an acceptable relationship with pH_electrode values, with R2 of 0.50 and 0.48, respectively. These methods, however, underestimated the average pH_electrodo values in 0.44 and 0.21 pH units, respectively. When the value of pH_electrodo was estimated by organic carbon, pH_T or pH_T_RL showed acceptable fits were obtained and the average differences between pH_electrodo and estimated pH_electrodo were -0.02 and 0.24 units, respectively. Therefore, would be no differences when assigning soils to acidity classes if pH were measured by pH_T_RL methods or estimated by pH_T or pH_T_RL and organic carbon. The pH measured by strip can be used as value to classify soil acidity if previously a calibration based on SOC contents and pH measurements by electrode was made.

Published
2015-12-01
How to Cite
1.
Beretta A, Bassahun D, Musselli R, Torres D. Soil pH Measurement with Reactive Paper Test Agrociencia Uruguay - Volumen 19 2:68-74 - julio/diciembre 2015 The pH test papers (strips) may be useful for measuring soil pH. The pH values for. Agrociencia Uruguay [Internet]. 1Dec.2015 [cited 21Oct.2020];19(2):68-74. Available from: http://agrocienciauruguay.uy/ojs/index.php/agrociencia/article/view/303
Section
Soil and Water