Nitrification as Affected by Temperature and Moisture Content of Mulched Soils
1962
Parker, D. T. | Larson, W. E.
In the temperature range of 16° to 20°C., a 2°C. differential in soil temperature had a measurable effect on the rate of conversion of NH₄-N to NO₃-N. However, as soil temperature increased to the range of 25° to 30°C. or as the supply of NH₄-N became limiting, differences in NO₃-N production resulting from small differences in soil temperature were not observed. In field soil, very early in the season when soil temperature was in the range of 16° to 20°C., mulched soil was 1° to 2°C. cooler than bare soil. During this period greater accumulation of NO₃-N could occur in bare than in mulched soil as a result of the temperature difference. As measured in the laboratory, NO₃-N production was retarded at soil moisture tensions below 50 cm. of water. At still higher moisture levels, considerable mineral N was lost from the soil. Measurements in the field showed that the soil moisture content of mulched soil exceeded that of bare soil. For short periods of time the moisture level of mulched soil was high enough to cause retarded nitrification and loss of N.
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