Biochar, which can
be produced using organic wastes such as agricultural residues, sewage sludge,
or wood chips, has become a product of interest for carbon sequestration, as a
soil amendment for crop yield improvement and for bioremediation in recent
years.
Most rhizobial
inoculants that stimulate legume yield are applied with carriers that enhance
root contact. The physicochemical properties of biochar are suitable for
microbial growth, and it could be an alternative to peat, which comes from
decreasing reserves but is the commonest solid inoculant carrier. The aim of
the current research was to evaluate biochars as carriers of bradyrhizobia in
solid inoculant and as coatings for seeds.
In this study, four
types of biochar were used: two from hardwood feedstock: Dynamotive-DM (West
Lorne, Ontario, Canada) and Basque-BQ (Rimouski, Québec); and two from softwood
feedstock: BlueLeaf-BL (Drummondville, Québec) and Pyrovac-PR (Saguenay,
Québec). Peat moss-PM was the control inoculant carrier (PRO-MOSS TBK,
Rivière-du-Loup, Québec). And biochars and peat were inoculated with Bradyrhizobium
japonicum strain 532C and storage time was assessed. A seed coating
system was developed using biochar, bacteria liquid culture, water, and guar
gum. The viability of bacteria in the coating and in solid biochar was
evaluated at 4°C and 21°C. Two biochars were selected for a germination assay.
Finally, greenhouse experimentation investigated the effect of biochar
inoculant and seed coating on soybean growth and nutrient uptake.
The storage time
experiment showed that not all biochars equally sustain bacteria survival over
time. The germination assay demonstrated that biochar seed coating had no
effect on soybean germination. Greenhouse experimentation indicated that the
effect of Pyrovac biochar on soybean growth characteristics and nutrient uptake
depended on the fertilizer. The main finding was that biochar solid inoculant
positively affected plant growth metrics, root characteristics, and the
chemical composition of plants supplied with N-free nutrient solution.
Article by Martyna Głodowska, et al,
from Canada.
Full access: http://mrw.so/x9wMQ
Image by DeAnn Peterson, from
Flickr-cc.
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