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Yahia Mahmoud

Senior lecturer

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Biochar production and application in small-scale farming in Kenya : Yield increases and local perceptions


  • Yahia Mahmoud
  • James K Gitau
  • Erik Karltun
  • Thomas Kätterer
  • Geoffrey Kimutai
  • Mary Njenga
  • Gert Nyberg
  • Kristina Roing de Nowina
  • Dries Roobroek
  • Cecilia Sundberg

Summary, in English

Degradation of agricultural soils and forest resources are two pervasive challenges in rural landscapes of sub-Saharan Africa. Biochar-producing biomass gasification technologies attract evermore interest because these can empower small-scale farmers to produce energy and food more sustainably by
improving energy use efficiencies, lowering emissions and strengthening climate resilience. In order to assess the potential impacts and the feasibility of soil biochar amendments we are carrying out on-farm trials with 150 households in three agroecosystems in Kenya. A participatory approach was followed for testing uptake of gasifier cook stoves and effects of biochar use on crop production. The outcomes that will be presented include: (a) the degree of feasibility, (b) the effects on crop yields, (c) the general attitudes towards the idea of using the cookstoves to produce biochar, and (d) patterns of biomass fuel use. Effects of domestically produced biochar, at rates of 1-10 t DW ha-1, on the production of maize (Zea mays) and kale (Brassica oleracea) were compared with normal farming practices. At the site located in Kwale the yield increases of maize showed a strong positive correlation with biochar dose. In the first season, yields increased from 0.9 Mg ha-1 in the control plot to 4.4
Mg ha-1 in average in the biochar-amended plots. At another site (Siaya), an average biochar dose of 2.8 Mg ha-1 lead to an increase in maize yields from 2.9 to 3.8 Mg ha-1 in average in the first season and from 1.7 to 2.5 Mg ha-1 in the second season after biochar addition. Findings from this action research indicate that producing and using biochar on small-scale farms offers suitable opportunities to close yield gaps across Kenya and in similar agro-ecological environments.


  • Department of Human Geography

Publishing year




Document type

Conference paper: abstract


  • Social Sciences Interdisciplinary


  • Biochar
  • Soil carbon mineralisation
  • Sustainable development

Conference name

Agricultural Research for Development Conference 2019

Conference date

2019-09-25 - 2019-09-26

Conference place

Uppsala, Sweden