Possibilities to improve soil aggregate stability using biochars derived from various biomasses through slow pyrolysis, hydrothermal carbonization, or torrefaction

Jaakko Heikkinen (Corresponding Author), Riikka Keskinen, Helena Soinne, Jari Hyväluoma, Johanna Nikama, Hanne Wikberg, Anssi Källi, Virpi Siipola, Thierry Melkior, Capucine Dupont, Matthieu Campargue, Sylvia H. Larsson, Markus Hannula, Kimmo Rasa

Research output: Contribution to journalArticleScientificpeer-review

1 Citation (Scopus)

Abstract

Various thermochemical conversion technologies can be applied in producing biochar from a wide range of raw materials. We studied the chemical quality of 10 different biochars produced via torrefaction (TOR), slow pyrolysis (SP), or hydrothermal carbonization (HTC), in order to assess their potential in improving clay soil aggregate stability and thus contribute to mitigation of erosion from agricultural soils. X-ray tomography was used to visualize soil aggregates in some selected biochar treatments. Feedstock type had a major influence on the properties of the biochar, but in general biochars derived through SP were alkaline and exhibited higher electrical conductivity and ash content and lower surface activity than acidic HTC and TOR biochars. Alkyl peak areas determined from FTIR spectra were higher in biochars produced by TOR and HTC than in SP biochars, which indicates a higher degree of hydrophobicity in the former. Significantly higher aggregate stability and reduced colloid detachment were achieved with HTC biochars, most likely due to hydrophobicity reducing wetting rate and aggregate slaking. When mixed with initially aggregated soil, the biochar particles settled in inter-aggregate voids. According to image analysis, the internal porosity of soil aggregates was not affected by biochar addition, i.e., biochar did not enter the aggregates during the short incubation period. Addition of hydrophobic HTC biochar decreased the soil water content at field capacity, whereas more inert SP chars tended to increase it. The overall effect of biochar hydrophobicity on soil functions needs to be explored prior to wider use of biochar as a soil amendment.

Original languageEnglish
Pages (from-to)40-49
Number of pages10
JournalGeoderma
Volume344
DOIs
Publication statusE-pub ahead of print - 7 Mar 2019
MoE publication typeNot Eligible

Fingerprint

torrefaction
biochar
aggregate stability
soil aggregate
pyrolysis
soil aggregates
hydrophobicity
biomass
slaking
field capacity
soil amendment
colloid
clay soil
agricultural soil
wetting
image analysis
void
tomography
electrical conductivity
mitigation

Cite this

Heikkinen, Jaakko ; Keskinen, Riikka ; Soinne, Helena ; Hyväluoma, Jari ; Nikama, Johanna ; Wikberg, Hanne ; Källi, Anssi ; Siipola, Virpi ; Melkior, Thierry ; Dupont, Capucine ; Campargue, Matthieu ; Larsson, Sylvia H. ; Hannula, Markus ; Rasa, Kimmo. / Possibilities to improve soil aggregate stability using biochars derived from various biomasses through slow pyrolysis, hydrothermal carbonization, or torrefaction. In: Geoderma. 2019 ; Vol. 344. pp. 40-49.
@article{da83e29f62124fa780c22053e0d8f786,
title = "Possibilities to improve soil aggregate stability using biochars derived from various biomasses through slow pyrolysis, hydrothermal carbonization, or torrefaction",
abstract = "Various thermochemical conversion technologies can be applied in producing biochar from a wide range of raw materials. We studied the chemical quality of 10 different biochars produced via torrefaction (TOR), slow pyrolysis (SP), or hydrothermal carbonization (HTC), in order to assess their potential in improving clay soil aggregate stability and thus contribute to mitigation of erosion from agricultural soils. X-ray tomography was used to visualize soil aggregates in some selected biochar treatments. Feedstock type had a major influence on the properties of the biochar, but in general biochars derived through SP were alkaline and exhibited higher electrical conductivity and ash content and lower surface activity than acidic HTC and TOR biochars. Alkyl peak areas determined from FTIR spectra were higher in biochars produced by TOR and HTC than in SP biochars, which indicates a higher degree of hydrophobicity in the former. Significantly higher aggregate stability and reduced colloid detachment were achieved with HTC biochars, most likely due to hydrophobicity reducing wetting rate and aggregate slaking. When mixed with initially aggregated soil, the biochar particles settled in inter-aggregate voids. According to image analysis, the internal porosity of soil aggregates was not affected by biochar addition, i.e., biochar did not enter the aggregates during the short incubation period. Addition of hydrophobic HTC biochar decreased the soil water content at field capacity, whereas more inert SP chars tended to increase it. The overall effect of biochar hydrophobicity on soil functions needs to be explored prior to wider use of biochar as a soil amendment.",
author = "Jaakko Heikkinen and Riikka Keskinen and Helena Soinne and Jari Hyv{\"a}luoma and Johanna Nikama and Hanne Wikberg and Anssi K{\"a}lli and Virpi Siipola and Thierry Melkior and Capucine Dupont and Matthieu Campargue and Larsson, {Sylvia H.} and Markus Hannula and Kimmo Rasa",
year = "2019",
month = "3",
day = "7",
doi = "10.1016/j.geoderma.2019.02.028",
language = "English",
volume = "344",
pages = "40--49",
journal = "Geoderma",
issn = "0016-7061",
publisher = "Elsevier",

}

Heikkinen, J, Keskinen, R, Soinne, H, Hyväluoma, J, Nikama, J, Wikberg, H, Källi, A, Siipola, V, Melkior, T, Dupont, C, Campargue, M, Larsson, SH, Hannula, M & Rasa, K 2019, 'Possibilities to improve soil aggregate stability using biochars derived from various biomasses through slow pyrolysis, hydrothermal carbonization, or torrefaction', Geoderma, vol. 344, pp. 40-49. https://doi.org/10.1016/j.geoderma.2019.02.028

Possibilities to improve soil aggregate stability using biochars derived from various biomasses through slow pyrolysis, hydrothermal carbonization, or torrefaction. / Heikkinen, Jaakko (Corresponding Author); Keskinen, Riikka; Soinne, Helena; Hyväluoma, Jari; Nikama, Johanna; Wikberg, Hanne; Källi, Anssi; Siipola, Virpi; Melkior, Thierry; Dupont, Capucine; Campargue, Matthieu; Larsson, Sylvia H.; Hannula, Markus; Rasa, Kimmo.

In: Geoderma, Vol. 344, 07.03.2019, p. 40-49.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - Possibilities to improve soil aggregate stability using biochars derived from various biomasses through slow pyrolysis, hydrothermal carbonization, or torrefaction

AU - Heikkinen, Jaakko

AU - Keskinen, Riikka

AU - Soinne, Helena

AU - Hyväluoma, Jari

AU - Nikama, Johanna

AU - Wikberg, Hanne

AU - Källi, Anssi

AU - Siipola, Virpi

AU - Melkior, Thierry

AU - Dupont, Capucine

AU - Campargue, Matthieu

AU - Larsson, Sylvia H.

AU - Hannula, Markus

AU - Rasa, Kimmo

PY - 2019/3/7

Y1 - 2019/3/7

N2 - Various thermochemical conversion technologies can be applied in producing biochar from a wide range of raw materials. We studied the chemical quality of 10 different biochars produced via torrefaction (TOR), slow pyrolysis (SP), or hydrothermal carbonization (HTC), in order to assess their potential in improving clay soil aggregate stability and thus contribute to mitigation of erosion from agricultural soils. X-ray tomography was used to visualize soil aggregates in some selected biochar treatments. Feedstock type had a major influence on the properties of the biochar, but in general biochars derived through SP were alkaline and exhibited higher electrical conductivity and ash content and lower surface activity than acidic HTC and TOR biochars. Alkyl peak areas determined from FTIR spectra were higher in biochars produced by TOR and HTC than in SP biochars, which indicates a higher degree of hydrophobicity in the former. Significantly higher aggregate stability and reduced colloid detachment were achieved with HTC biochars, most likely due to hydrophobicity reducing wetting rate and aggregate slaking. When mixed with initially aggregated soil, the biochar particles settled in inter-aggregate voids. According to image analysis, the internal porosity of soil aggregates was not affected by biochar addition, i.e., biochar did not enter the aggregates during the short incubation period. Addition of hydrophobic HTC biochar decreased the soil water content at field capacity, whereas more inert SP chars tended to increase it. The overall effect of biochar hydrophobicity on soil functions needs to be explored prior to wider use of biochar as a soil amendment.

AB - Various thermochemical conversion technologies can be applied in producing biochar from a wide range of raw materials. We studied the chemical quality of 10 different biochars produced via torrefaction (TOR), slow pyrolysis (SP), or hydrothermal carbonization (HTC), in order to assess their potential in improving clay soil aggregate stability and thus contribute to mitigation of erosion from agricultural soils. X-ray tomography was used to visualize soil aggregates in some selected biochar treatments. Feedstock type had a major influence on the properties of the biochar, but in general biochars derived through SP were alkaline and exhibited higher electrical conductivity and ash content and lower surface activity than acidic HTC and TOR biochars. Alkyl peak areas determined from FTIR spectra were higher in biochars produced by TOR and HTC than in SP biochars, which indicates a higher degree of hydrophobicity in the former. Significantly higher aggregate stability and reduced colloid detachment were achieved with HTC biochars, most likely due to hydrophobicity reducing wetting rate and aggregate slaking. When mixed with initially aggregated soil, the biochar particles settled in inter-aggregate voids. According to image analysis, the internal porosity of soil aggregates was not affected by biochar addition, i.e., biochar did not enter the aggregates during the short incubation period. Addition of hydrophobic HTC biochar decreased the soil water content at field capacity, whereas more inert SP chars tended to increase it. The overall effect of biochar hydrophobicity on soil functions needs to be explored prior to wider use of biochar as a soil amendment.

UR - http://www.scopus.com/inward/record.url?scp=85062386073&partnerID=8YFLogxK

U2 - 10.1016/j.geoderma.2019.02.028

DO - 10.1016/j.geoderma.2019.02.028

M3 - Article

AN - SCOPUS:85062386073

VL - 344

SP - 40

EP - 49

JO - Geoderma

JF - Geoderma

SN - 0016-7061

ER -