Temperature Sensitivity of Nitrogen Dynamics of Agricultural Soils of the United States

Abstract

Soil temperature controls gaseous nitrogen losses through nitrous oxide (N 2 O) and ammonia (NH 3 ) fluxes. Eight surface soils from agricultural fields across the United States were incubated at 10 ° C, 20 ° C, and 30 ° C, and N 2 O and NH 3 flux were measured twice a week for 91 and 47 d, respectively. Changes in cumulative N 2 O and NH 3 flux and net N mineralization at three temperatures were fitted to calculate Q 10 using the Arrhenius equation. For the majority of soils, Q 10 values for the N 2 O loss ranged between 0.23 and 2.14, except for Blackville, North Carolina (11.4) and Jackson, Tennessee (10.1). For NH 3 flux, Q 10 values ranged from 0.63 (Frenchville, Maine) to 1.24 (North Bend, Nebraska). Net soil N mineralization-Q 10 ranged from 0.96 to 1.00. Distribution of soil organic carbon and total soil N can explain the variability of Q 10 for N 2 O loss. Understanding the Q 10 variability of soil N dynamics will help us to predict the N loss.