Accumulation of NO2− during periods of drying stimulates soil N2O emissions during subsequent rewetting. (26th June 2018)

• Record Type: Journal Article
• Authors: Liu, S.; Schloter, M.; Brüggemann, N.
• Is Part Of: European journal of soil science. Volume 69:Number 5(2018)
• Page Start: 936
• Page End: 946
• Publication Date: 2018-06-26
• Subjects: Soil science -- Periodicals; 631.4
• DOI: 10.1111/ejss.12683
• Languages: English
• ISSNs: 1351-0754

Abstract

Summary: Rewetting of soil might contribute considerably to the annual production of nitrous oxide (N2 O) in ecosystems subjected to long dry periods. Therefore, it is crucial to elucidate the most important factors responsible for large pulses of N2 O with rewetting. In this study, we carried out a series of rewetting experiments with soil samples collected from upland and riparian forest, grassland and arable land. We analysed the dynamics of ammonium (NH4 + ), nitrite (NO2 − ), nitrate (NO3 − ) and dissolved organic matter (DOM) of air‐dried soil samples after rewetting. We also analysed the effects of sterilization of soil samples by γ‐irradiation on N2 O production with rewetting. Furthermore, we explored the effects of rewetting and sterilization on the isotopic composition of N2 O in the different soil samples. The grassland soil produced the largest amount of N2 O (64.1 μg N kg −1 ) in 1 hour on rewetting, followed by upland forest soil, whereas it was least for soils from riparian forest and arable land. Gamma irradiation, however, decreased soil N2 O production from forest soil samples by 30–90% after rewetting, but increased N2 O production in grassland and arable land soils three‐fold and two‐fold, respectively. Correlation analysis revealed that NO2 − concentration in the soil samples at the time of rewetting was the most relevant factor that explained soil N2 O production after rewetting. Furthermore, the addition of NO2 − before rewetting increased N2 O production during rewetting more than with additions of NO3 − and NH4 + in all soil samples. The 15 N site preference values of N2 O produced after rewetting were close to 0‰, indicating a denitrification‐related production process according to the classical view. However, additional abiotic processes responsible for soil N2 O production during rewetting cannot be excluded. Highlights : Mechanisms responsible for large N2 O production during rewetting of soil are not well understood. Nitrite content in dry soil was strongly correlated with N2 O production after rewetting. The 15 N site preference of the N2 O produced was close to 0‰ after rewetting. Additional abiotic processes could have contributed to N2 O formation from NO2 − .