Impact of Biochar Formulation on the Release of Particulate Matter and on Short-Term Agronomic Performance

Abstract

When applied in agriculture, the solid carbonaceous residue of anoxic thermochemical conversion of biomass (biochar) has variable effects on soil, crop yields, and climate mitigation. Biochar can be added to soil as powder or as pellets. While powdered forms have demonstrated effects on crop yields, they may release coarse and fine particulate that can be transported into the atmosphere during production, packaging, storage, transport, and distribution. Biochar weathering and wind erosion may also cause the release of particles. Particulate matter (PM) released from biochar may have negative effects on human health and increase the atmospheric burden of shortwave absorbing black carbon aerosols with non-negligible effects on atmospheric radiative forcing. Pelletizing feedstock before the thermochemical conversion and moistening of biochar are expected to reduce the emission of PM in the processing and post-processing phases while also increasing the mean residence time of Carbon in soils. The impact of biochar formulation (pellet and non-pellet) on the release of coarse and fine particulate in wet and dry conditions was assessed in a laboratory experiment. In parallel, the effects of pellet and non-pellet formulations on growth and yield of processing tomato plants were tested in a pot experiment. Results show that pelletization and moistening substantially reduce the amount of fine particles released and are therefore practices that should be adopted to maximize the mitigation potential of biochar. A reduction of tomato yield was observed in pellet treatment, suggesting that the higher interface area of powdered biochar may boost productivity in the short term. This work points to the existence of a tradeoff between the short-term maximization of agronomic benefits and the minimization of harmful effects due to particulate release.

Structural and Functional Features of Chars From Different Biomasses as Potential Plant Amendments

“…Pelletizing chars could improve the handling procedures but on the other hand might decrease the large surface and microporosity, which are some of the main positive properties of char ( Erlich et al, 2006 ; Karkania et al, 2012 ). Wetting biochar is probably a better solution to control small particles ( Maienza et al, 2017 ), as is the case with some of the chars studied here.…”

Unexplored potential of novel biochar-ash composites for use as organo-mineral fertilizers

“…Moreover, pelletising of biochar reduced the release of fine particles, and hence increased the carbon sequestration potential of biochar and decreased the health risk due to dust formation during biochar application (Maienza et al, 2017). We expect that our biochar-ash composite M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT has similar effects, which will be the focus of follow-up studies.…”

Variation of Greenhouse Gases Fluxes and Soil Properties with Addition of Biochar from Farm-Wastes in Volcanic and Non-Volcanic Soils

“…This could partly explain our results as the BC used was previously sieved at 250 µm to guarantee a complete incorporation with soil into experimental mesocosm; this particle-size probably had lower pore connectivity and aeration, favouring anaerobic spaces that increase the methanogenic activity. Respect to particle-size of biochar, Genesio et al [56] indicate that particles smaller than 2.5 µm of black C could cause a positive radiative forcing when is transport to high altitudes (direct) or is deposited over ice or snow (indirect); for that in the production and others forms of manipulation the release of fine particles of BCs should be avoided, in this sense, Maienza et al [57] studied the impact of pellet and non-pellet formulations.…”