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Tropentag, September 17 - 19, 2018 in Ghent

"Global food security and food safety: The role of universities"

Effects of Biochar and the Use of TLUD"=Reactors in Rural Areas for Cooking and Soil

Götz Uckert1, Hannah A. Graef2, Ma Hua1, Frieder Graef3, Yusto Yustas4, Valerian Silayo5, Stefan Sieber1, Sonoko Dorothea Bellingrath-Kimura3, Harry Hoffmann1

1Leibniz Centre for Agric. Landscape Res. (ZALF), Inst. of Socio-Economics, Germany
2University of Rostock, Fac. of Agricultural and Environmental Sciences, Germany
3Leibniz Centre for Agric. Landscape Res. (ZALF), Inst. for Land Use Systems, Germany
4Sokoine University of Agriculture (SUA), Engineering Sci. and Techn., Tanzania
5Sokoine University of Agriculture (SUA), Agri. Engin. and Land Planning, Tanzania


On-farm crop residues are often left unutilised or not efficiently used. Often they are left to be decomposed or, sometimes, in situ used by livestock. Crop by-products, like maize cobs and residues from primary processing, especially from threshing and shelling, have a high percentage of lignified structural components and therefore are suitable for thermo-chemical conversion. A pyrolysis-treatment of these residues can provide thermal energy for cooking applications as well as for biochar production, which can be used as a soil amendment to improve soil structure and cation exchange capacity as well as to contribute to carbon sequestration. A top-lid-up-draft (TLUD) barrel-reactor was developed at the University of Hohenheim and iteratively adjusted (in the project of Trans-SEC) for the use at grass-root level, which led to a cooking extension of the device. It can be built from scrap material (oil drums) locally available and is capable of sustaining high temperatures of up to 400°C. The drum has a screw-top lid, and a central pipe with a diameter of 10 cm perforated with a dense array of 10 mm holes made throughout its height. Test results from the UPS farmers group in one of the case study villages showed that after pyrolysis for about two hours from 15 kg of maize cobs about 4.4 kg of biochar (29%) could be produced. In the poster we will discuss the amount of biochar amendment needed to increase soil fertility and crop productivity for certain farming areas and site conditions derived from data of field trials with soybean and grains in China and Germany and different maize cropping systems in Tanzania. According to soil types and water regimes we found different yield responds after biochar application. Recommended rates of 5-10 (up to 20) tons biochar per hectare limit the suitability to small gardens or need to extend the size of the reactor to the scale of a big charcoal kiln.

Keywords: Biochar, charcoal, crop residues, energy stacking, energy transition, field trials, pyrolyzer, soil improvement, woodfuel

Contact Address: Götz Uckert, Leibniz Centre for Agric. Landscape Res. (ZALF), Inst. of Socio-Economics, Eberswalder Str. 84, 15374 Müncheberg, Germany, e-mail: uckert@zalf.de

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