How Do Different pH Meters Compare? A Look at Soil pH Meters: Store-bought, Portable Scientific Meters, and Analytical Lab pH Meters

Homeowners visit the University of Florida, Institute of Food and Agricultural Sciences (UF/IFAS) Extension St. Lucie County, seeking solutions for unhealthy plants. They are advised to send soil samples to the UF/IFAS Extension Soil Testing Laboratory (ESTL) for pH analysis. Clients informed Agents they intend to utilize store-bought pH meters. This experiment aimed to determine whether pH meters in ESTL and store-bought pH meters produced similar results. One hundred fifteen St. Lucie County residents were surveyed. Questions included: a) have you measured your soil pH, and if so, how?; b) have you ever used a store-bought soil pH meter, and c) do you feel that these types of pH meters are accurate? 64% (n = 74) of respondents believed store-bought pH meters are accurate, 32% (n = 37) stated store-bought pH meters may or may not be accurate, and 4% (n = 4) stated that store-bought pH meters are not accurate. To test the accuracy of store-bought pH meters, a soil sample was submitted to the University of Florida Extension Soil Testing Lab (ESTL), and three store-bought pH meters were also used. For pH testing, soil samples were collected from three different sites. The results of the three store-bought pH meters were compared with those of one portable scientific pH meter and the pH results from the ESTL. Results from the portable scientific pH meters and the ESTL were very similar. Results from store-bought pH meters were significantly different from those of the portable scientific pH meters and pH results from the ESTL. Store-bought soil pH meters produce inconsistent readings. Since store-bought pH meters are inaccurate, they should not be substituted for scientific pH meters or those used in the university’s soil testing laboratory.