Abstract:
Woody biochars derived by pyrolyzing Gliricidia sepium at 300°C and 500°C and
a waste byproduct of same biomass from a bioenergy industry (BC700) were
tested for their effect on soil enzymes activities and available form of heavy
metals in multi-metals contaminated soil. Pot experiments were conducted
during 6 weeks with tomato (Lycopersicon esculentumL.) at biochar application
rates, 1, 2.5, and 5% (w/w). A reduction in polyphenol oxidase with biochars
produced at increasing pyrolysis temperature compared to the control
whereas the maximum activity of dehydrogenase and catalase was observed
in 1% BC500 and 2.5% BC300, respectively. Soil available form of Ni, Mn, and Cr
were reduced by 55, 70% and 80% in 5% BC700 amended soil, respectively.
The highest geometric mean of enzyme activities was observed in 2.5% BC300
treatment. Overall the application of high dosages of high temperature
derived biochar masks/deteriorates soil enzyme activities but immobilizes
bioavailable heavy metals and reduces toxicity.
