Abstract
The resilience of microbial functions like carbon (C) and nitrogen (N) cycling to stress is likely heavily dependent on pH. Past research, however, has been limited to laboratory manipulations or a pH gradient resulting from differences in soil mineralogy. In this study, soils were collected from a >50-year field trial where plots have been maintained at pH 4.9, 6 and 7.1. We selected copper (Cu) and heat to represent persistent and transient stresses, respectively. Changes in C mineralization, ammonia oxidation, denitrification, and gene (16S rRNA, nirK, nirS and amoA) abundance were immediately measured after heat- (40 °C for 16 hours) and Cu- (500 µg Cu soil g-1 or 1 mg Cu soil g-1 17 ) induced stresses, during subsequent recovery over 56 days, and compared to an unstressed control. Higher soil pH significantly increased C mineralization (by 217%), ammonia oxidation (by 617%), and the gene abundances of 16S rRNA (by 77%), nirK (by 976%) and nirS (by 997%). Soil pH had a significant (P < 0.001) selection effect on the phylotypes of bacterial communities and ammonium oxidising
bacteria (AOB). Ammonia oxidation was significantly (P < 0.05) more resistant and resilient to both Cu stresses in the pH 7.1 soil. C mineralization in the soil at pH 7.1 was significantly (P < 0.05) more resilient to low Cu than the soil at pH 4.9. Correspondingly, significantly (P < 0.001) distinct bacterial communities were present in these soils, indicating that bacterial composition triggered by the adaptation and tolerance to stress is a central factor governing functional resilience. Denitrification in the pH 7.1 soil was significantly (P < 0.05) more resilient to low and high Cu, compared to the soil at pH 4.9. Similarly, the abundances of nirS and nirK genes were greater in the higher pH soil. Although
soil pH directly affects Cu but not heat stress, our results indicated that neutral soils harboured greater resilience of C and N cycling to both Cu (persistent) and heat (transient) stresses
bacteria (AOB). Ammonia oxidation was significantly (P < 0.05) more resistant and resilient to both Cu stresses in the pH 7.1 soil. C mineralization in the soil at pH 7.1 was significantly (P < 0.05) more resilient to low Cu than the soil at pH 4.9. Correspondingly, significantly (P < 0.001) distinct bacterial communities were present in these soils, indicating that bacterial composition triggered by the adaptation and tolerance to stress is a central factor governing functional resilience. Denitrification in the pH 7.1 soil was significantly (P < 0.05) more resilient to low and high Cu, compared to the soil at pH 4.9. Similarly, the abundances of nirS and nirK genes were greater in the higher pH soil. Although
soil pH directly affects Cu but not heat stress, our results indicated that neutral soils harboured greater resilience of C and N cycling to both Cu (persistent) and heat (transient) stresses
| Original language | English |
|---|---|
| Article number | 104690 |
| Journal | Applied Soil Ecology |
| Volume | 182 |
| DOIs | |
| Publication status | Published - Feb 2023 |
Bibliographical note
AcknowledgementThe authors acknowledge the international studentship funded by Scotland’s Rural College. We thank the help from John Parker, Susan Mitchell, and Adrian Langarica-Fuentes in setting up these experiments. For the purpose of open access, E M Baggs has applied a Creative Commons Attribution (CC BY) licence to any Author Accepted Manuscript version arising from this submission.
Keywords
- soil ph
- microbial community
- stability
- nutrient cycling
- Cu
- heat