Abstract: Biochar, a co-product of a controlled pyrolysis process, can be used as a tool for
sequestering C in soil to offset greenhouse gas (GHG) emissions, and as a soil amendment.
Whereas the impacts of biochar application on soil chemical properties are widely known,
the research information on soil physical properties is scarce. The objectives of this review
are to (i) synthesize available data on soil physical properties and GHG emissions, (ii) offer
possible mechanisms related to the biochar-amended soil processes, and (iii) identify
researchable priorities. Application rates of 1%–2% (w/w) of biochar can significantly
improve soil physical quality in terms of bulk density (BD), and water holding capacity
(WHC). However, little data are available on surface area (SA), aggregation stability, and
penetration resistance (PR) of biochar-amended soil. While biochar amendment can
initially accentuate the flux of carbon dioxide (CO2), the emission of GHGs may be
suppressed over time. A 2-phase complexation hypothesis is proposed regarding the
mechanisms of the interaction between soil and biochar.
Keywords: biochar; green house gas (GHG) emissions; soil amendment; soil physical
properties; soil quality