Asynchronous pulse responses of soil carbon and nitrogen mineralization to rewetting events at a short-term: Regulation by microbes

Rewetting after precipitation events plays an important role in regulating soil carbon (C) and nitrogen (N) turnover processes in arid and semiarid ecosystems. Here, we conducted a 48-h rewetting simulation experiment with measurements of soil C and N mineralization rates (R (C) and R (N), respectively) and microbial biomass N (MBN) at high temporal resolution to explore the pulse responses of R (C) and R (N). R (C) and R (N) responded strongly and rapidly to rewetting over the short term. The maximum R (C) value (because of pulse effects) ranged from 16.53 to 19.33 µg C g(soil) (−1) h(−1), observed 10 min after rewetting. The maximum R (N) varied from 22.86 to 40.87 µg N g(soil) (−1) h(−1), appearing 5–6 h after rewetting. The responses of soil microbial growth to rewetting were rapid, and the maximum MBN was observed 2–3 h after rewetting. Unexpectedly, there was no correlation between R (C), R (N), and MBN during the process of rewetting, and R (C) and R (N) were uncoupled. In sum, the pulse responses of R (C), R (N), and microbial growth to simulated rewetting were rapid, strong, and asynchronous, which offers insights into the different responses of microbes to rewetting and mechanisms behind microbes.