Open Access

ARTICLE

Effects of Biochar Particle Size on Methane Emissions from Rice Cultivation

Patikorn Sriphirom^1,2, Amnat Chidthaisong^1,2,3, Kazuyuki Yagi^1,2, Nimaradee Boonapatcharoen⁴, Sudarut Tripetchkul⁵, Sirintornthep Towprayoon^1,2,3,*

1 The Joint Graduate School of Energy and Environment, King Mongkut’s University of Technology Thonburi, Bangkok, 10140, Thailand
2 Center of Excellence on Energy Technology and Environment, PERDO, Ministry of Higher Education, Science, Research and Innovation, Bangkok, 10400, Thailand
3 Earth System Science Research Cluster, King Mongkut’s University of Technology Thonburi, Bangkok, 10140, Thailand
4 Excellent Center of Waste Utilization and Management, Pilot Plant Development and Training Institute, King Mongkut’s University of Technology Thonburi, Bangkok, 10150, Thailand
5 School of Bioresources and Technology, King Mongkut’s University of Technology Thonburi, Bangkok, 10150, Thailand

* Corresponding Author: Sirintornthep Towprayoon. Email:

(This article belongs to the Special Issue: Renewable materials for sustainable development)

Journal of Renewable Materials 2020, 8(10), 1199-1214. https://doi.org/10.32604/jrm.2020.010826

Received 03 April 2020; Accepted 23 June 2020; Issue published 31 August 2020

Abstract

Biochar amendment is generally recognized as an effective mitigation option of methane (CH₄) emissions from rice cultivation. Although its mitigation mechanisms are not well understood, the potential relevance of surface area and porosity of biochar has been discussed. This study aimed to evaluate the application of different biochar particle sizes on CH₄ production, oxidation, and emissions from rice cultivation in a clay loam soil, based on the assumption that porosity and surface area of biochar are directly related to its mitigation effects. Rice was grown under greenhouse conditions for two growing seasons, either with 0.5–2 mm (small, SB) or with 2–4 mm (large, LB) biochar. The results show that both sizes of biochar increased soil pH and redox potential (Eh) during rice growth. Soil dissolved organic carbon (DOC), nitrate (NO₃⁻ ), and sulfate (SO₄²⁻) also increased under both biochar amendments, but size effects were not observed. SB and LB suppressed the abundance of CH₄ producers (methanogens) but stimulated the abundance of CH₄ consumers (methanotrophs). The increase of soil Eh and electron acceptors (NO₃⁻ and SO₄²⁻ ) indicated the increase in soil oxidation capacity is a barrier to CH₄ production by methanogens in both biochar treatments. Laboratory incubation experiments showed that CH₄ production activity was significantly (p ≤ 0.05) reduced by 18.5% using SB and by 11.3% using LB compared to the control. In contrast, the stimulation of methanotrophs promoted greater CH₄ oxidation activity by 15.0% in SB and 18.7% in LB compared to the control. It shows that CH₄ production was reduced more by larger surface area biochar (SB), while a greater increase in CH₄ oxidation was found using larger pore volume biochar (LB). The effects on CH₄ production were more pronounced than those on CH₄ oxidation, resulting in a greater reduction of cumulative CH₄ emissions by SB than LB (by 26.6% and 19.9% compared to control, respectively).

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