Liquid chemical fertilizers are widely used in modern agriculture. The pH values of these fertilizers
are important in terms of their effectiveness in the field application and their effect on the soil-water
pH balance. Therefore, it is necessary to measure the pH and other properties of liquid fertilizers
with fast, practical and inexpensive methods. With the advancing technology, pH value has been
started to measure more accurately and efficiently with the help of low-cost devices. In this study, a
low-cost pH meter was developed using a low-cost pH sensor, an Arduino UNO R3 microcontroller
board, and a software written in the C/C++ programming language. The developed pH meter was
used to measure the pH values of liquid chemical fertilizers. Close variations were observed between
the values obtained from it and the values measured by an accredited, laboratory-type pH meter.
According to the pH measurements of the two pH meters, R2 ranged 88.1% to 99.3%, average error
range 0.14 to 0.28, and average error percentage ranged 1.56% to 6.81% for three different types of
liquid fertilizers. In light of these results, it was shown that the developed low-cost pH meter can be
useful for practical pH measurement applications
