Skip to main content
Real-time multi ISFET/FIA soil analysis system with automatic sample extraction
Computers and Electronics in Agriculture
  • Stuart J. Birrell, Iowa State University
  • John W. Hummel, United States Department of Agriculture
Document Type
Publication Date
Successful implementation of site-specific crop management relies on accurate quantification of spatial variation of important factors. Therefore, there is a tremendous need for the development of sensing technologies that will allow automated collection of soil, crop and pest data, to more accurately characterize within-field variability. The objective of this work was to develop an integrated multi-sensor soil analysis system. Ion-selective field effect transistor (ISFET) technology was coupled with flow injection analysis (FIA) to produce a real-time soil analysis system. Testing of the ISFET/ FIA system for soil analysis was carried out in two stages: (1) using manually extracted samples, and (2) the soil to be analysed was placed in the automated soil extraction system, and the extracted solution fed directly into the FIA system. The sensor was successful in measuring soil nitrates in manually extracted soil solutions (r2>0.9). The rapid response of the system allowed a sample to be analysed in 1.25 s, which is satisfactory for real-time soil sensing. Precision and accuracy of the system were highly dependent on maintaining precise, repetitive injection times and maintaining constant flow parameters during the calibration and testing cycle. The progress toward an automated soil extraction system was notable, but considerable effort will be necessary before commercialization can be realized. However, the concept of using ISFETs for the real-time analysis of soil nitrates is sound. The rapid response and low sample volumes required by the multi-sensor ISFET/FIA system make it a viable candidate for use in real-time soil nutrient sensing.

This article is from Computers and Electronics in Agriculture 32 (2001): 45–67, doi:10.1016/S0168-1699(01)00159-4.

Works produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted.
File Format
Citation Information
Stuart J. Birrell and John W. Hummel. "Real-time multi ISFET/FIA soil analysis system with automatic sample extraction" Computers and Electronics in Agriculture Vol. 32 Iss. 10 (2001) p. 45 - 67
Available at: