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A method for determination of NO3‐ in waters using an NH3 electrode was adapted for use with soils. Nitrate was determined in 1 N KCl soil extracts as the difference in NH3‐N concentration between aliquots treated with NaOH and Devarda's alloy to reduce NO3‐ and aliquots made alkaline without addition of Devarda's alloy. The rate of reduction of NO3‐ to NH3 was temperature dependent. The minimum recommended temperature for the procedure is 23°C. Rate of NH3 loss from solution and NH3 activity measured by the NH3 electrode increased with temperature.Nitrate‐N in extracts of nine Illinois soils determined with the NH3 electrode was highly correlated (r2 = 0.999***)3 with NO3‐‐N analyzed by the phenoldisulfonic acid method. Exchangeable NH4+‐N determined with the modified electrode filling solution was highly correlated (r2 = 0.99***) with exchangeable NH4+‐N determined by steam distillation. In addition to NO3‐, NO2‐ is reduced to NH3 by this procedure. Recovery of added NH4+, NO3‐, and NO2‐ was 97, 97, and 91%, respectively. Precision of NO3‐ and exchangeable NH4+ determinations were 0.2 and 0.1 mg/kg, respectively. The reagents used are relatively inexpensive and safe to handle, and reduction is carried out at room temperature. Only 20 ml of soil extract is required and soils containing 1 to 250 mg NO3‐‐N/Kg can be handled routinely. One worker can analyze 80 extracts/day.