Development and modelling of a soil nitrate and potassium simultaneous rapid detection system based on ion selective electrodes

Abstract

Conventional soil nitrate and potassium detection methods are reliable, but time‐consuming and expensive. Rapid lower‐cost detection methods for soil nitrate and potassium are urgently needed. In this study, a tem perature‐calibrated soil nitrate and potassium rapid simultaneous detection system was developed based on two ion‐selective electrodes (ISEs). At room temperature, the potentiometric experiments were conducted to evaluate the performance of both ISEs and simple linear regression (SLR) was used for modelling. The lower detection limits of both ISEs were 1 × 10‐5 mol/litre with regression coefficients of 0.994 and 0.997, respectively. Under different temperatures, the potentiometric experiments were conducted and multiple SLRs were used for temperature‐calibrated modelling with a maximum relative error of c. 6% and c. 10%, respectively. An ISE signal acquisition system was developed based on a microprocessor, including an ISE signal conditioning unit and a temperature measurement unit using a thermal resistor. This study might be suitable for in‐field soil nitrate and potassium rapid detection application.