Microbial mechanism of biochar addition to reduce N2O emissions from soilless substrate systems

Xiaofeng Liang; Wanlai Zhou; Rui Yang; Dongdong Zhang; Hong Wang; Qiaozhen Li; Zhiyong Qi; Yuzhong Li; Wei Lin

doi:10.1016/j.jenvman.2023.119326

Microbial mechanism of biochar addition to reduce N₂O emissions from soilless substrate systems

J Environ Manage. 2023 Dec 15:348:119326. doi: 10.1016/j.jenvman.2023.119326. Epub 2023 Oct 14.

Authors

Xiaofeng Liang¹, Wanlai Zhou², Rui Yang², Dongdong Zhang², Hong Wang², Qiaozhen Li³, Zhiyong Qi⁴, Yuzhong Li⁵, Wei Lin⁶

Affiliations

¹ College of Mechanical Engineering, Chengdu University, Chengdu, 610106, PR China. Electronic address: 1602703834@qq.com.
² Institute of Urban Agriculture, Chinese Academy of Agricultural Sciences, Chengdu, 610213, PR China.
³ Environmental Stable Isotope Lab., Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences, Beijing, 100081, PR China.
⁴ College of Mechanical Engineering, Chengdu University, Chengdu, 610106, PR China; Institute of Urban Agriculture, Chinese Academy of Agricultural Sciences, Chengdu, 610213, PR China.
⁵ Environmental Stable Isotope Lab., Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences, Beijing, 100081, PR China. Electronic address: liyuzhong@caas.cn.
⁶ Institute of Urban Agriculture, Chinese Academy of Agricultural Sciences, Chengdu, 610213, PR China; Environmental Stable Isotope Lab., Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences, Beijing, 100081, PR China. Electronic address: linwei01@caas.cn.

PMID: 37844399
DOI: 10.1016/j.jenvman.2023.119326

Abstract

The soilless peat-based substrate partially solves the global soil problem in greenhouse vegetable production. However, it still produces serious N₂O emissions due to the application of nutrient solutions. The pyrolysis biochar is regarded as an effective measure to reduce soil N₂O emissions. However, the effect and mechanism of biochar on N₂O emissions from the soilless substrate remain unknown. Therefore, this study set up six treatments by adjusting the ratio of biochar addition of peat-based substrate: 0% (0BC), 2% (2BC), 4% (4BC), 6% (6BC), 8% (8BC) and 10% (10BC) (v/v). The results showed that compared to the control treatment, N₂O emissions reduced by 81%, 71%, 51%, 61%, and 75% in the 2BC, 4BC, 6BC, 8BC and 10BC treatments, respectively. In addition, lettuce yield increased by 10% and 7% in the 2BC and 4BC treatments and decreased by 0.5%, 4% and 6% in the 6BC, 8BC and 10BC treatments, respectively. Combining stable isotope technology, qPCR analysis and high-throughput sequencing, five microbial pathways of N₂O production, including bacterial and archaea nitrification (BN and AN), denitrification performed by fungi, denitrifier bacteria and nitrifier bacteria (FD, DD and ND), were roughly distinguished. In addition, the extent of N₂O reduction was obtained by δ¹⁸O vs.δ¹⁵N^SP map. For all treatments, overall, the DD process (over 50%) was the main process of N₂O production and reduction, while ND and AN processes were almost negligible (less 5%). In detail, the decrease of N₂O emissions was caused by decreasing the contribution of FD in the 6BC, 8BC and 10BC treatments and reducing the contribution of BN in the 0BC and 2BC treatments. In addition, biochar addition increased the extent of N₂O reduction to N₂. In summary, the 2% biochar addition presented the greatest extent of N₂O reduction to N₂ (83%) and the lowest N₂O emissions as well as the highest lettuce yields and nitrogen utilization efficiency. Therefore, 2% biochar is deemed the most optimal addition to the peat-based substrate.

Keywords: Biochar; Fungal denitrification; Molecular biotechnology; N(2)O reduction; Stable isotope.

MeSH terms

Bacteria / metabolism
Charcoal / metabolism
Fertilizers* / analysis
Lactuca / metabolism
Nitrous Oxide* / metabolism
Soil

Substances

biochar
Nitrous Oxide
Fertilizers
Charcoal
Soil