TY  - EJOU
AU  - Sriphirom, Patikorn 
AU  - Chidthaisong, Amnat 
AU  - Yagi, Kazuyuki 
AU  - Boonapatcharoen, Nimaradee 
AU  - Tripetchkul, Sudarut 
AU  - Towprayoon, Sirintornthep 

TI  - Effects of Biochar Particle Size on Methane Emissions from Rice Cultivation
T2  - Journal of Renewable Materials

PY  - 2020
VL  - 8
IS  - 10
SN  - 2164-6341

AB  - Biochar amendment is generally recognized as an effective mitigation
option of methane (CH<sub>4</sub>) 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 CH<sub>4</sub> 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 (NO<sub>3</sub><sup>−</sup>
), and sulfate (SO<sub>4</sub><sup>2−</sup>)
also increased under both biochar amendments, but size effects were not
observed. SB and LB suppressed the abundance of CH<sub>4</sub> producers (methanogens)
but stimulated the abundance of CH<sub>4</sub> consumers (methanotrophs). The increase of
soil Eh and electron acceptors (NO<sub>3</sub><sup>−</sup> and SO<sub>4</sub><sup>2−</sup>
) indicated the increase in soil oxidation capacity is a barrier to CH<sub>4</sub> production by methanogens in both biochar
treatments. Laboratory incubation experiments showed that CH<sub>4</sub> 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 CH<sub>4</sub> oxidation activity by 15.0% in SB and 18.7% in LB compared
to the control. It shows that CH<sub>4</sub> production was reduced more by larger surface
area biochar (SB), while a greater increase in CH<sub>4</sub> oxidation was found using larger pore volume biochar (LB). The effects on CH<sub>4</sub> production were more pronounced than those on CH<sub>4</sub> oxidation, resulting in a greater reduction of
cumulative CH<sub>4</sub> emissions by SB than LB (by 26.6% and 19.9% compared to
control, respectively).
KW  - Biochar particle size; CH4 production; CH4 oxidation; CH4 emission; rice cultivation

DO  - 10.32604/jrm.2020.010826