 |
| Titel |
Physicochemical changes in pyrogenic organic matter (biochar) after 15 months of field aging |
| VerfasserIn |
A. Mukherjee, A. R. Zimmerman, R. Hamdan, W. T. Cooper |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1869-9510
|
| Digitales Dokument |
URL |
| Erschienen |
In: Solid Earth ; 5, no. 2 ; Nr. 5, no. 2 (2014-07-23), S.693-704 |
| Datensatznummer |
250115319
|
| Publikation (Nr.) |
 copernicus.org/se-5-693-2014.pdf |
|
|
|
|
|
| Zusammenfassung |
| Predicting the effects of pyrogenic organic matter (OM) addition (either
natural or intentional as in the case of biochar amendment) on soil
chemistry and crop yields has been hampered by a lack of understanding of
how pyrogenic OM evolves in the environment over time. This work compared
the physicochemical characteristics of newly made and 15-month-field-aged
biochars and biochar–soil mixtures. After aging, biochars made by pyrolysis
of wood and grass at 250, 400 and 650 °C exhibited 5-fold increases in
cation exchange capacity (CEC), on average; appearance of anion exchange
capacity (AEC); and significant decreases in pH, ash content and nanopore
surface area. Cross polarization 13C nuclear magnetic resonance (NMR) analyses indicated relative
increases in O-containing functional groups, including substituted aryl,
carboxyl and carbonyl C, and losses of O-alkyl groups. Similar chemical
trends were observed for soil–biochar mixtures, suggesting the same biochar
aging processes occurred in the soil environment. However, there was
evidence for a role of soil OM–microbe–biochar interaction during aging.
Field aging of soil with biochar resulted in large increases in C and N
content (up to 124 and 143%, respectively) and exchange capacity (up to
43%) beyond that calculated by the weighted addition of the properties of
biochar and soil aged separately. These beneficial interactive effects
varied with soil and biochar type. Scanning electronic microscopy (SEM)
images of biochar particles aged with soil showed colonization by microbes
and widespread OM coatings. Thus, sorption of both microbially produced and
soil OM are likely processes that enhanced biochar aging. Thus, biochar's
full beneficial effects on soil properties likely increase over time, and
proper assignment of C sequestration credits to biochar users will require
consideration of soil–biochar interactions. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|