Application of ion sensitive field effect transistor (ISFET) for the analysis of soil pH, nitrate and available potassium

Abstract

This paper describes the application of ISFET technology in analyzing the soil sample and correlating it with the convectional soil testing method. These devices can offer sensitive, selective, reliable, and often cheap measurements for an ever increasing diversity of sensing requirements. These sensors are procured from Microsens, Switzerland and the circuitry of ISFETs was made with the help of Elico Pvt Ltd. The experiment setup was done in ICAR-IISS, Bhopal. The soil sample were of the order Vertisol, Inceptisol and Alfisol and its analysis for soil pH, nitrate and available potassium was performed through ISFET. Also covering the conditioning and calibration procedures for ISFET. Furthermore limitation of ISFET of ISFET regarding linearity range, drift and sensitivity have been discussed. The reported sensitivity for obtained was 56.8mV/decade, 34mV/decade and 60mV/ decade for pH, Nitrate and potassium respectively. The correlation results with convectional method was significant in case of pH with R2 = 0.95. On the other hand nitrate and potassium showed R2 = 0.59 and 0.63 respectively in which further improvement is needed.