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

Xiaoli Song,Jing Tian,Jianxing Zhu,Yuan Liu,Xiang Zhao,Nianpeng He,Changhui Wang,Jianhui Huang

doi:10.1038/s41598-017-07744-1

Abstract

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 (RC and RN, respectively) and microbial biomass N (MBN) at high temporal resolution to explore the pulse responses of RC and RN. RC and RN responded strongly and rapidly to rewetting over the short term. The maximum RC value (because of pulse effects) ranged from 16.53 to 19.33 µg C gsoil−1 h−1, observed 10 min after rewetting. The maximum RN varied from 22.86 to 40.87 µg N gsoil−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 RC, RN, and MBN during the process of rewetting, and RC and RN were uncoupled. In sum, the pulse responses of RC, RN, 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.

Highlights

Periodic rewetting of soil after precipitation events is common and exerts a significant influence on the carbon (C) and nitrogen (N) cycles of an ecosystem[1,2,3]
Based on a 48-h incubation experiment of soil C mineralization rate (RC, 6-min intervals), N mineralization rate (RN, 18 times), and microbial biomass nitrogen (MBN, 18 times) at high temporal resolution, we investigated the dynamics of RC, RN, and microbial biomass N (MBN) in two semi-arid forest soils through a simulation of rewetting
No significant relationships between RC and MBN were observed from the early stages through the peaking of RC during the 48-h incubation period

Summary

Introduction

Periodic rewetting of soil after precipitation events is common and exerts a significant influence on the carbon (C) and nitrogen (N) cycles of an ecosystem[1,2,3]. Birch H.F5 first reported that precipitation events after long-term or severe drought lead to strong and rapid increases in soil respiration and microbial biomass through a pulse or priming effect. No study has focused on the short-term pulse effects of precipitation events or rewetting on both soil C and N turnover from minutes to several days. Through the pulse effects of rewetting, microbial biomass and activity in soil first increase sharply, rapidly decomposing soil organic matter (SOM) to satisfy microbial requirements for energy and elements (C, N, and P) within a very short time. The main objectives of this study were (1) to investigate the short-term dynamics of RC, RN, and MBN after rewetting; (2) to quantify the pulse effects of simulated rewetting on RC and RN; and (3) to discuss the underlying mechanisms influencing RC and RN in initial phase of rewetting event.

Objectives

Methods

Results

Conclusion