|Title||ROLE OF WOODY BIOCHAR ON SOIL MICROBIAL ACTIVITIES, ORGANIC FRACTION AND HEAVY METAL IMMOBILIZATION IN SERPENTNE SOIL|
|Publication Type||Journal Article|
|Year of Publication||2014|
|Authors||Bandara, Tharanga, Hewage Bhagya, Herath Indika, Kumarathilaka Prasanna, Yapa Priyantha, Wekumbura Chandima, Rajakaruna Prasanna, Dissanayake Shiromi, and Vithanage Meththika|
|Journal||DRIVING RESEARCH TOWARDS ECONOMY: OPPORTUNITIES AND CHALLENGES|
Serpentine soil is rich in heavy metals resulting unfavorable conditions for plants. Biochar is a novel soil amendment with an ability to remediate pollutants environmental friendly manner. In this study, biochar (BC) was examined as a potential soil amendment on the activity of soil microorganisms and heavy metal immobilization in serpentine soil. The BCs (BC300, BC500 and BC700) were prepared by slow pyrolysis of Gliricidia sepium biomass at three different temperatures (i.e. 300, 500 and 700 0C) with a residence time of 2 h. A pot experiment was conducted for 6 weeks with tomato (Lycopersicon esculentum L.) with the presence of three different ratios, 1, 2.5 and 5% (w/w), of BCs to soil. Polyphenol oxidase, catalase and dehydrogenase enzyme activities were determined by using idometric, potassium permanganate oxidisable and spectrophotometric methods respectively. Total organic carbon (TOC) was determined by using wet oxidation by acidified dichromate method while soil microbial biomass (MBC) carbon was analyzed by CHCl3 fumigation method. CaCl2 extraction method was used to quantify bioavailability of heavy metals (Ni, Mn and Cr). Incorporation of BC reduced polyphenol oxidase and catalase activity with increasing pyrolysis temperature. Dehydrogenase activity showed no pattern and the maximum was found in 2.5% BC300 which was 91-fold increase compared to the control. The maximum TOC and MBC were observed in BC300 and BC500 at 5% amendments, respectively. In addition, bioavailability of heavy metals was significantly reduced, 92% for Ni, 94% for Mn and 100% for Cr, in 5% BC700 compared to control. Results suggested that the addition of BC into serpentine soil immobilizes heavy metals significantly, while decreasing soil enzymatic activities and increased soil TOC and MBC.