Dynamics of soil N2O emissions and functional gene abundance in response to biochar application in the presence of earthworms

Yupeng Wu; Jiao Liu; Muhammad Shaaban; Ronggui Hu

doi:10.1016/j.envpol.2020.115670

Dynamics of soil N₂O emissions and functional gene abundance in response to biochar application in the presence of earthworms

Environ Pollut. 2021 Jan 1;268(Pt A):115670. doi: 10.1016/j.envpol.2020.115670. Epub 2020 Sep 29.

Authors

Yupeng Wu¹, Jiao Liu², Muhammad Shaaban³, Ronggui Hu⁴

Affiliations

¹ College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, China.
² College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, China; School of Environment, Beijing Normal University, Beijing, 100875, China.
³ Department of Soil Science, Faculty of Agricultural Sciences and Technology, Bahauddin Zakariya University, Multan, Pakistan. Electronic address: [email protected].
⁴ College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, China. Electronic address: [email protected].

PMID: 33022546
DOI: 10.1016/j.envpol.2020.115670

Abstract

Nitrous oxide (N₂O) is a devastating greenhouse gas and acts as an ozone-depleting agent. Earthworms are a potential source of soil N₂O emissions. Application of biochar can mitigate earthworm-induced N₂O emissions. However, the underlying interactive mechanism between earthworms and biochar in soil N₂O emissions is still unclear. A 35-day laboratory experiment was conducted to examine the soil N₂O emission dynamics for four different treatments, earthworm presence with biochar application (EC), earthworm presence without biochar application (E), earthworm absence with biochar application (C) and earthworm absence without biochar application, and the control. Results indicated a negative impact of biochar on earthworm activity, displaying a significantly (p ≤ 0.05) lower survival rate and biomass of earthworms in treatment EC than E. Compared with the control, earthworm presence significantly (p ≤ 0.05) increased cumulative N₂O emissions, while application of biochar in the presence of earthworms significantly (p ≤ 0.05) decreased cumulative N₂O emissions (485 and 690 μg kg^-1 for treatments EC and E, respectively). Treatments E and EC significantly (p ≤ 0.05) increased soil microbial biomass carbon (MBC), ammonium (NH₄⁺-N), nitrate (NO₃^-N), and dissolved organic carbon (DOC) content and soil pH as compared with the control. The gene copy number of 16 S rRNA, AOA, AOB, nirS, and nosZ increased for all treatments when compared with the control; however, a significant (p ≤ 0.05) difference among the studied genes was only observed for the nosZ gene (2.05 and 2.56 × 10⁶ gene copies g^-1 soil for treatments E and EC, respectively). Earthworm-induced soil N₂O emissions were significantly (p ≤ 0.05) reduced by biochar addition. The possible underlying mechanisms may include: (1) short-term negative impacts on earthworm activity; (2) a change of functional gene abundance in earthworm casts; and (3) an increase in soil pH due to addition of biochar.

Keywords: Biochar; Earthworm; Gene abundance; Mineral N; N(2)O; Organic C.

MeSH terms

Animals
Charcoal
Nitrous Oxide / analysis
Nitrous Oxide / toxicity
Oligochaeta*
Soil*

Substances

Soil
biochar
Charcoal
Nitrous Oxide