Characterization of tree bark biochar and evaluation of its potential to use in horticultural growing mediums

Conference Dates

September 15-20, 2019


Peat is popular in horticulture industry as a main constituent in the horticultural growing medium due to its high water holding capacity, improve aeration in the medium, ability to adjust the pH and fertility level in the substrate as required and pathogen freeness. However, the use of peat in growing mediums cause for the environmental problems such as greenhouse gas emissions due to excavating and drainage of natural peatlands. As a sustainable approach and an alternative to peat, biochar is getting attention due to its stable nature. As a byproduct of pyrolysis, biochar has high porosity, high pH, high cation exchange capacity (CEC) and high water holding capacity. These properties make biochar as an appropriate constitute in growing medium applications with long term plant productivity. Within this context, the aim of this study was to examine the potential of biochar produced from bark as an alternative to peat use in growing mediums. Biochar was characterized for elemental, proximate, organic matter content, pH, EC, Py GC-MS and FT-IR. Then, five growing medium substrates including peat only, biochar only, biochar and peat in 1:1, 1:3, 3:1 (V/V) ratios were analyzed for pH, electrical conductivity (EC), CEC, bulk density, porosity, water holding capacity, aeration, and particle size distribution parameters. Germination test was carried out to assess the phytotoxicity of the formulated substrates. Preliminary plant growth test was carried out to determine the tomato seedling growth up to four weeks. Additionally, one month of laboratory incubation was conducted to determine the pore water nutrient dynamics. For that, nitrate-N, phosphate-P and sulphate-S in rhizone extractions in each growing medium formulations were collected weekly up to one month of period. Addition of biochar into peat increased the pH, EC, and CEC of all peat and biochar mixed treatments. According to the germination test results for the cress, lettuce and tomato seeds, the addition of biochar into peat had significantly increased the germination percentage, shoot and root length of the germinated seeds compared to the peat only treatment. Addition of bark biochar into peat significantly increased the plant growth parameters compared to peat only and biochar only treatments. Nitrate-N, sulphate-S and phosphate-P content in pore water of each substrate were significantly high in biochar added treatments compared to the peat only treatment. These results indicate that bark biochar could use to partially replace peat use in horticultural growing mediums.

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