Household biochar production and use by smallholder farmers in Kenya

About 40% of the world population lack access to clean cooking fuels. In rural sub-Saharan Africa the majority of people prepare their meals with firewood on open three stone fires. Biochar-producing microgasification cookstoves provide an opportunity to reduce fuel consumption and reduce the indoor air pollution in the cooking area, while use of biochar in soils sequesters carbon and increases agricultural yields, thereby improving livelihoods, especially for women. This paper presents findings from transdisciplinary research that started with long-term biochar field trials established in 2006. During recent years this research has involved 150 farming households at 3 locations in Kenya that produce biochar in locally manufactured GASTOV Top-lit Updraft (TLUD) gasifier cookstoves and use the biochar in their own fields. Fuel use, indoor concentrations of CO, CO2 and PM2.5 in cooking areas, and biochar production potential was measured in 75 households during cooking of a common Kenyan meal. The produced biochar was used in field trials with maize (Zea mays) and kale (Brassica oleracea) comparing biochar to normal farming practices, at biochar doses of 1-10 t ha-1. Findings from one of the sites, in Kwale County, show that for cooking a meal, on average 18 % of fuel was saved compared to the three stone open fire. In addition, 200 g biochar were produced which corresponded to 16.5% of the biomass used. Concentrations of CO and PM2.5 were reduced by 57 and 79 %, respectively. Fuel use was dominated by the wood types neem (Azadirachta indica) and casuarina (Casuarina equisetifolia), but a large variety of wood types were used by the households. Yield increases of maize in Kwale correlated positively with biochar dose. For the 20 farmers that finalized the trials 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. In addition to presentation of data on biochar production, we present data on biochar quality and use from all three sites. Implications and prerequisites for long-term success and upscaling will be discussed. This research contributes to knowledge on adoption of improved cookstoves by investigating how biochar production can be an additional incentive for cookstove uptake. Furthermore, it contributes to the understanding of biochar production potential in African rural areas. This case study shows that biochar systems in rural Africa can contribute to climate change mitigation. Biochar technology can at the same time help to solve the problems with energy and food security that farmers are facing, and thereby contribute to sustainable development

Effective Striga control and yield intensification on maize farms in western Kenya with N fertilizer and herbicide-resistant variety

Open Access Article; Published online: 04 Apr 2023Context Maize production in western Kenya is limited by the spread of parasitic weed Striga hermonthica and depletion of soil nutrient stocks. Nitrogen (N) fertilizer and imidazolinone resistant (IR) maize are key elements in the agronomic toolbox to control infestations and enhance yields Research question The circumstances under which their use, individually or combined, is most effective on farmer fields have not been well documented. Inappropriate management decisions and low returns on investments arise from this knowledge gap, causing hunger and poverty in smallholder communities to persist. Methods Experiments were carried out on 60 fields in three different agroecosystems of western Kenya using full-factorial treatments with non-herbicide treated maize (DH) and herbicide treated maize (IR), and N fertilizer omission and application. Trials were stratified on a field with low and high soil fertility within individual farms and repeated over two seasons. Results Cultivating IR maize instead of DH maize decreased the emergence of Striga with 13 shoots m−2 on average while applying N fertilizer on DH maize led to a reduction of 5 shoots m−2 on average. Decreases of Striga by use of IR maize and N fertilizer were between 6 and 23 shoots m−2 larger at the site with high levels of infestation than at the sites with medium or low emergence. Input of N fertilizer increased grain harvests by 0.59 ton ha−1 on average while use of IR maize enhanced the productivity with 0.33 ton ha−1 on average. Use of N fertilizer had similar yield effects in all three sites, whereas use of IR maize at the site with high Striga emergence increased maize production by 0.26–0.39 ton ha−1 more than at the sites with medium or low emergence. Conclusions The greater Striga responses to IR maize and the greater yield responses to N fertilizer demonstrate their use could be optimized according to field conditions and management goals. Combining IR maize and N fertilizer has larger added yield benefits where their individual effects on grain productivity are smaller. Significance Findings from this study indicate that farmers in western Kenya require guidance on how to align the use of herbicide resistant maize and inorganic N inputs with the level of Striga infestation and maize yield on their fields for effectively controlling the pernicious weed and enhancing food production

Initial nitrous oxide fluxes from a maize-legume cropping system in a soil of the derived savanna zone of Nigeria-effect of fertilizer and incorporated organic matter

Legume—maize crop rotations are used as a mechanism to reverse declining soil fertility in West Africa. However, such crop rotations exhibit a relatively low recovery of legume N. Temperate region studies partly attribute low N recovery to gaseous N losses, but this has not been established for most cropping systems in the moist tropical savannas. The effect of incorporating added organic residues and fertilizer application on gaseous N20 ?uxes was studied in a ?eld trial at the International Institute of Tropical Agriculture (IITA), Ibadan (7, °30'N, 3 °S4'E) in the derived savanna zone of Nigeria. Gaseous N2O ?uxes were obtained 1, 3, 5, 8, and 15 days after incorporation of organic residues using a vented closed chamber system. Fluxes were examined in relation to soil mineral N status and rainfall patterns. Fertilizer application and incorporation of Pueraria phaseoloides organic residue increased soil mineral N contents as well as gaseous NZO ?uxes. Over the 15-day period, the total NZO fluxes were in the range of 21-30 mg N m2 for P. phaseoloides and 12-15 mg N m2 for natural fallow. Fertilizer-derived NZO ?uxes were less than 1% of applied fertilizer N

Initial nitrous oxide fluxes from a maize-legume cropping system in a soil of the derived Savanna zone of Nigeria-effect of fertilizer and incoporated organic matter

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Knowledge, attitude and practices used in the control of Striga in maize by smallholder farmers of western Kenya

The production of maize is constrained by parasitic weeds, particularly Striga. A study was carried out to document farmers’ knowledge, attitude and practices on Striga control among smallholder farmers across three districts: Kisumu West, Busia and Teso South of Western Kenya. A multistage sampling technique was used to select the locations and farmers to be interviewed. A semi structured, open and closed ended questionnaire was administered leading to field experiment. Besides village meetings (39.2%), farmers got informed on farming methods under Striga weed farms and its control technologies through neighbours (2.5%), workshops and trainings (5.0%), field schools (3.7%), media (7.5%) and extension agents (10.8%). The attitudes of farmers towards Striga control varied but frequently cited: long term viability of the Striga seed (12.5%), difficult to control sharing of farm tools (10.8%), expensive technologies (13.3%), lack of adequate information (18.3%), labour intensive (15.0%), large farms for use of push and pull technology (1.7%) and time consuming (12.5%). Framers used various Striga control practices but traditional methods (25%) were among the most used (25%). Concerted effort involving researchers, extension agents and private sector are, therefore, required for wide scale dissemination and adoption of the existing modern control technologies

Gasifier as a cleaner cooking system in rural Kenya

Published online: 17 February 2016Global demand for wood fuel energy is high and rising due to population increases, particularly in sub-Saharan Africa, where firewood and charcoal are the main sources of cooking energy. Inefficient cooking techniques consume large amounts of fuel and create indoor pollution, with negative health impacts particularly among women and small children. Efficient cooking stoves can potentially save fuel and reduce the health risks of smoke in the kitchen. This study compared the ease of use, energy consumption, fuel use efficiency and gas and particle emissions of a small-scale gasifier cooking stove with that of a traditional three-stone stove and an improved Hifadhi stove in a smallholder farming setting in Kenya. This was done by participatory evaluation of these cooking techniques by women on smallholder farms, assessing fuel consumption, time used in cooking and indoor air concentrations of carbon monoxide and fine particulate matter. It was found that compared with traditional and improved cooking stoves, the gasifier domestic cooking system saved 27–40% of fuel, reduced cooking time by 19–23% and reduced emissions by 40–90%. Thus the gasifier system has potential to alleviate energy and time poverty among small-scale farmers, while improving kitchen air quality. These new findings can assist in development of cleaner biomass cooking technologies in developing countries. Women who cooked using the gasifier preferred it to current cooking practices due to perceived benefits. Thus the gasifier is appropriate for rural areas; it constitutes a cleaner cooking system that saves fuel, produces charcoal for another round of cooking, cooks rapidly, and reduces indoor air pollution from cooking with biomass fuel. However, there is a need to improve the design to make it more stable and safer

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

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 byimproving 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 4.4Mg 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

Biochar from cookstoves reduces greenhouse gas emissions from smallholder farms in Africa

Biochar produced in cookstoves has the potential to contribute to negative carbon emissions through sequestration of biomass carbon while also providing other benefits for sustainable development, including provision of clean renewable energy and increased yields in tropical agriculture. The aim of the reported research was to estimate effects on food production, household energy access and life cycle climate impact from introduction of biochar-producing cookstoves on smallholder farms in Kenya. Participatory research on biochar production and use was undertaken with 150 Kenyan smallholder farming households. Gasifier cookstove functionality, fuel efficiency and emissions were measured, as well as biochar effects on agricultural yields after application to soil. Cookstoves provided benefits through reduced smoke, fuel wood savings and char production, but challenges were found related to labour for fuel preparation, lighting and refilling. On-farm trials with varying rates of biochar inputs, in combination with and without mineral fertilizers, have led to a sustained increase of maize yields following one-time application. The climate impact in a life cycle perspective was considerably lower for the system with cookstove production of biochar and use of biochar in agriculture than for current cooking practices. Climate benefits from biochar production and use are thus possible on smallholder farms in sub-Saharan Africa, through reduced use of biomass in cooking, reduced emissions of products of incomplete combustion and sequestration of stable biochar carbon in soils. Biochar-producing cookstoves can be implemented as a climate change mitigation method in rural sub-Saharan Africa. Successful implementation will require changes in cooking systems including fuel supply, as well as farming systems, which, in turn, requires an understanding of local socio-cultural conditions, including power relations and gender aspects