RAPID NITRATE ANALYSIS OF SOIL CORES USING ISFETS

Abstract

An intact core extraction procedure was tested that might be used in the field for realtime prediction of soilnitrates. An extraction solution was pushed through a soil core held between two filters, and an ionselective fieldeffecttransistor/flow injection analysis (ISFET/FIA) system was used to sense soil nitrates in real time. Laboratory tests wereconducted using four soil types and two levels of nitrate concentration, soil moisture, core density, core length, core diameter,and extraction solution flow rate. The extraction solution flow was sampled at the exit face of the core and routed to theISFET/FIA system. The ISFET output voltage was sampled at 100 Hz. Results of the test indicate that nitrate extraction ofthe soil cores was successful, and that data descriptors based on response curve peak and slope of the ISFET nitrate responsecurve might be used in tandem in a realtime prediction system.