The Effect of Time and Temperature on Nitrogen Mineralization in Arctic Tundra Soils

Abstract

Abstract The objective of this work was to evaluate several mathematical models for describing N mineralization in three arctic tundra soils (Histic Pergelic Cryaquepts) as functions of time and temperature. Intact soil cores were collected in the field and incubated in a laboratory at 5, 15, 25, and 35 °C for 11 weeks. The exponential equation fit the data well at 35 °C but was generally unsuited for describing N mineralization at lower temperatures. The parabolic equation better fit the N mineralization data than the exponential equation except in a few cases where the data appeared to be approaching an asymptote. The parameters of the parabolic equation did not follow simple trends with respect to temperature, however, which made interpolating between experimental temperatures difficult. A second‐order polynomial equation with respect to both time and temperature was evaluated. This empirical equation gave R 2 >0.98 in all but one case. The major advantages of the empirical, polynomial equation are that it assumes little about the nature of the N mineralization process, it is flexible, and it is accurate. The temperature data did not follow the Arrhenius relationship nor have a simple overall Q 10 value because the mineralization rates at different temperatures did not follow similar trends with respect to time. Only a small fraction of the N that is potentially mineralizable is likely to be mineralized under the prevailing cold temperatures of these arctic soils.