Nitrogen Mineralization in a Tussock Tundra Soil

Abstract

The effects of substrate quality, temperature, and moisture on nitrogen mineralization from a tussock tundra soil were examined with laboratory soil incubations utilizing both air-dried samples and field-moist intact cores. The potentially mineralizable nitrogen (PMN) was highly correlated to both total soil nitrogen (positively) and the carbon/nitrogen ratio (negatively). All soil horizons exhibited a net nitrogen mineralization even at a high carbon/nitrogen ratio of 92. It was concluded that field-moist intact soil cores provide a more reliable estimate than the air-dried samples of both PMN and the mineralization rate under standard laboratory conditions. There was no significant effect of moisture tension (0.0 to 0.4 bars) on net nitrogen mineralization. The average Q₁₀ (temperature effect) for net nitrogen mineralization was 2.5. Based on this study and others, it was concluded that temperature through its effect on nitrogen mineralization plays an important role in controlling plant productivity in these naturally nitrogen-deficient tundra ecosystems.