The effect of oven-drying on residual inorganic nitrogen in soils

Abstract

Residual ammonium nitrogen in soils which were dried in an oven increased, whereas residual nitrate nitrogen remained almost constant. This observation led to experiments which help to explain the accumulation of ammonium nitrogen in oven-dried soils. It was found that the temperature-dependent rate of accumulation of exchangeable ammonium nitrogen in heated air-dried soils decreased if heating was prolonged, but accumulation itself continued for long periods. More ammonium accumulated in organic than in mineral soils. Nitrate nitrogen neither accumulated nor was it destroyed. The contribution of thermal decomposition to apparent residual ammonium nitrogen content should be borne in mind when soil samples are prepared for analysis.

Keywords:

• Ammonium
• drying temperature
• organic matter in soil
• soil heating
• thermal degradation