Determination of nitrate in soil pastes by ion selective electrodes

An ion selective electrode was used to measure the nitrate ion concentration in pastes of soil and saturated calcium sulphate solution. A good correlation, for both air‐dried and field‐moist soil samples, was obtained between nitrate values found by colorimetric analysis subsequent to KC1 extraction, and those found by a nitrate electrode, non‐porous reference electrode couple. A ceramic frit reference electrode, although effective in pastes of air‐dried soils, gave rise to erroneous results in pastes of field‐moist soils.