Differential Pulse Sensitivity of Nitric and Nitrous Oxide Emissions to Temperature, Carbon, and Nitrogen Following Wetting of Desert Soils

Infrequent soil wetting in deserts can induce large nitrogen (N) trace gas pulses; however, how other abiotic mechanisms interactively control the timing and magnitude of these pulses are not clear. In particular, production of nitric(NO) and nitrous (N 2 O) oxide may be differentially sensitive to temperature, carbon (C), and N availability. At a desert field site in Southern California, USA, we used an automated sensor system in 4 years of field campaigns to track NO and N 2 O pulse responses to experimental manipulations of C and N across a range of ambient temperatures and shrub fertile islands. We observed rapid onset and shorter duration of N 2 O pulses immediately after wetting compared to lagged and extended pulses of NO, suggesting preferential incorporation of N initially into N 2 O in anoxic microsites and then to NO as soils dry. We identified strong nitrogen limitation and exponential temperature dependence of NO pulses, particularly for soils located under shrubs. N 2 O pulses were less responsive to experimental manipulations but showed evidence of C and N colimitation as well as seasonal temperature differences. As atmospheric N deposition and temperatures continue to increase in desert systems, we can expect larger losses of N from soils as pulse‐based emissions.