Standard laboratory methods for measurement of soil nitrate (NO3–N) use various
procedures and instruments to analyze soil samples taken from the field and transported to
the laboratory. Concerns with these procedures range from delays in measurement time, the
high cost of soil sampling and analysis, high labour requirements, and the need to aggregate
samples. With recent advances in using the ion-selective electrode, as presented in this
chapter, soil NO3–N can now be measured directly, rapidly, accurately, at low cost, at a fine
scale, and in real-time right in the field....