STiR coffee and tea magazine

STiR coffee and tea 33 Even more amazing, once introduced it can hold carbon in soils for hundreds to thousands of years. It does not matter what feedstock the growers use: pruned twigs, green manure, leaves, coconut shells, spent tea, neem, ash from wood-fired dryers, or common weeds. Biochar is produced through pyrolysis or gasification ― techniques that do not give off CO2. Biochar is neither ash or soot. It contains a high concentration of cellu- lose. Carbonization is the thermochemical conversion of biomass in an oxygen-limited environment at temperatures below 700 centigrade. The process is called pyrolysis when no oxygen is present and gasification when small amounts of oxygen are used. The process mirrors the production of charcoal which generally requires heating wood chips to between 600 and 900 degrees Celsius. Biochar is simple to produce, sustainable, and climate friendly. Agricultural work- ers using biochar stoves experience lower exposure to carbon monoxide, smoke and particulates generated by open cooking fires. A common 55-gal. metal drum can be easily fashioned into a biochar kiln. What it can do During the 1980s Sri Lanka's department of agriculture introduced a low-temperature, low-cost method of using paddy husk to produce Kara anguru that rejuvenated soil quality and raised crop yields in rice paddies. Kara anguru is a type of low-grade bio- char. The Rubber Research Institute of Sri Lanka in 2009 advanced the concept by producing biochar from firewood used in rubber manufacturing. Adding biochar to the soil reduced fertilizer use, cut down on leaching and improved the growth of rub- ber trees. A slow-release urea fertilizer combination was developed using biochar. Mohotti explains that the porous, crystalline biochar structure absorbs bio-oils, nitrogen, phosphorus, and other nutrients. Biochar has a very high surface area ideal for holding water and food consumed by soil microorganisms. These nutrients are bioavailable to plants. "Another advantage is due to its compressed nature. A tiny amount is required whereas ordinary organic soil amendments such as agro wastes, oil cakes and composts etc. must be applied in kilograms and metric tons. In his office Mohotti displayed biochar made from several different feedstocks. "Paddy husk and coconut shell sources are the most promising," he said. To facilitate grower participation, his vision was to utilize locally available feed stocks to produce biochar using a simple unit as well as to provide sustainable avenues to the tea growers. So far, his research team has been successful in demonstrating how biochar works to enhance tea soils, reduce nitrogen leaching, capture soil elements including soil pesticides, and promote the enumeration of inherent beneficial soil organisms that strengthen root systems. The tea research institute is also working to charge biochar with soil nutrients and soil pesticides as a means of reducing dosage. "This will im- mensely benefit the environment while reducing the cost of inputs," he said. Garden trials When biochar was appplied at Rilhena Estate in Rakwana yields increased to 800 kilos of green leaves per hectare, as detailed in a June 2016 Tea Research Institute presentation by Mohotti. A conventional field in the experiment pro- duced 600 kilos per hectare. At Haring- ton Estate in Kotagala the application of biochar was demonstrated to increase the average number of kilos of made tea per hectare indicating healthy full leaves. Dilhan C. Fernando, a director at Dilmah tea writes that "Biochar is some- thing that I have enormous confidence in as an element in the future of our tea industry." Dr. Keerthi Mohotti, dep. dir. of research at the Sri Lanka Tea Research Institute

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