ASSERT: A Platform Technology for Rapid Electrochemical Sensing of Soil Ammonium

Area of Science:

• Agricultural Science
• Environmental Science
• Electrochemistry

Background:

• Inefficient farming practices and overfertilization disrupt soil ecosystems, impacting nutrient availability and carbon sequestration.
• Sustainable agriculture demands real-time soil health monitoring for efficient resource management and erosion prevention.

Purpose of the Study:

• To develop and validate an electrochemical ion-selective electrode (ISE) for in situ measurement of soil ammonium.
• To enable direct, continuous ammonium monitoring without soil pretreatment for improved agricultural practices.

Main Methods:

• An electrochemical ion-selective electrode (ISE) sensor was developed using electrochemical impedance spectroscopy.
• The sensor was drop-cast onto a working electrode and calibrated across three major soil textures (clay, sandy loam, loamy clay).
• Validation was performed against spectrophotometric methods and through a 16-day in situ soil study.

Main Results:

• The ISE demonstrated a highly linear, ammonium-dependent response (Pearson r > 0.991) across soil textures (2-32 ppm).
• Validation against spectrophotometry showed an error rate of less than 20%.
• In situ monitoring revealed robust stability with an 11% coefficient of variance over 16 days.

Conclusions:

• The developed ISE provides a reliable and stable method for in situ soil ammonium measurement.
• This sensor technology supports precision agriculture by offering real-time soil health data.
• The findings contribute to advancing sustainable farming practices and addressing food security challenges.