Transforming agricultural waste into biochar can potentially generate renewable energy, capture carbon, improve soil health, and mitigate climate change. However, its adoption is still minimal due to ambiguity in the realisation of associated benefits, as the evidence of its impact on crop yield based on on-farm data is very limited. In this study, we analysed a comprehensive dataset of 962 households across three states of India, viz. Madhya Pradesh, Maharashtra, and Odisha. Findings show that the application of biochar had a positive and significant effect on crop yield enhancement (4.34%) and net return (29.34%), and a reduction in cost of cultivation (1.52%). However, the effect size is much smaller than that reported in experimental studies conducted in controlled conditions. Farmers who are more experienced in farming, have irrigation facilities, and diversify crops and enterprises perceive benefits from biochar. Improvement in soil fertility is the primary benefit farmers perceive from biochar, whereas the limited availability of biochar and lack of incentives are the major constraints in adoption. The study suggests strategies and policies for outscaling and creating enabling environments for biochar production in Indian agriculture.
Tag: biochar
Interactions between regenerative strategies and edaphic, climatic and topographic factors mediate mitigation or exacerbation of soil and crop toxicity in global cadmium contaminated lands
Cadmium (Cd) contamination in agroecosystems is a global concern, due to its negative influence on soil health and crop performance. Regenerative strategies have been widely recognised as vital to improve soil quality and crop yields. Yet strategies are needed that also mitigate rather than exacerbate the impacts of Cd contamination. In this context, interactions between regenerative strategies, and edaphic, climatic and topographic factors are poorly understood. This study presents a meta-analysis with effect size statistics, evaluating the interactions between regenerative strategies (biochar, manure and compost), non- regenerative strategies (sewage-sludge and fertilizer), soil properties (pH, SOM and Cd levels), climatic factors (temperature and precipitation), and elevation. In acidic or high SOM soils, fertilizer increased Cd uptake by 50% to 76%. However, biochar or compost addition in these soils reduced Cd uptake. Under high Cd contamination, biochar application increased shoot biomass, but fertilizer application decreased shoot-biomass. The application of fertilizer or sewage-sludge under higher temperatures increased Cd uptake, whereas biochar reduced Cd uptake. At wet sites, fertilizer addition increased soil Cd accumulation. At high elevations, biochar was more effective than manure at reducing Cd accumulation. We conclude that there are complex interactions between regenerative strategies and environmental conditions; determining impacts on soil and crop health. The interactions between environmental factors and use of sewage-sludge or fertilizer could exacerbate soil and plant Cd toxicity. Regenerative strategies, especially biochar, could mitigate Cd toxicity in agroecosystems.
Early-stage sustainability assessment of greywater treatment with Moringa oleifera seed extract and biochar
Access to safe and reliable water remains a significant challenge in much of the Global South, especially in rural areas where greywater treatment infrastructure is lacking. This study presents an early-stage sustainability assessment of a novel system that utilises biochar and Moringa oleifera seed extracts to treat greywater in rural Kenyan households. The proposed solution combines local biochar, a by-product of wood gasification cookstoves, and powdered Moringa oleifera seed cake, a residue from local agroforestry activities. The presented assessment applied a qualitative approach that integrates life cycle, circular bioeconomy, and sustainable sanitation principles. The key sustainability opportunities involved in the assessed system include improved human health and hygiene, the carbon sequestration potential of biochar, greywater reuse, and efficient use of local biomass resources. However, the system also involves risks related to filter media disposal, nutrient loss and system maintenance. The analysis highlights the trade-offs between using Moringa oleifera seed cake for water purification and animal feed. Moreover, the early-stage assessment identifies the need for pilot trials, participatory design and data collection to develop future life cycle analyses and implementation strategies. This integrated approach provides a sound basis for the sustainable development of natural greywater treatment systems that meet the goals of a circular bioeconomy.
Mzee Mukoko’s legacy of regenerative farming
At 82, Mzee Mika Mukoko has transformed his modest two-acre farm in Vihiga County, Kenya, into an inspiring example of farmer-led agroecological innovation. A former wildlife conservationist trained in organic farming at the Rodale Institute (US), Mukoko blends traditional wisdom with modern science to create a lighthouse for regenerative agriculture. His farm demonstrates how smallholder farmers can achieve ecological resilience, economic viability, and community empowerment on limited land.
The foundation of his system is soil restoration. Mukoko produces biochar from crop residues and animal bones, crafts nutrient-rich Terra Preta compost, and applies fermented liquid fertilizers to revive degraded soils. For pest management, he deploys plant-based biopesticides, raised planting mounds for mole control and drainage, and diversified polycultures to maintain ecosystem balance. Space-efficient designs, including floating gardens, vertical cropping, and integrated multi-story systems, maximize yields while conserving biodiversity. These innovations have attracted over 25 bird species, boosted pollinator populations, and improved soil resilience to climate extremes.
Mukoko applies circular bioeconomy principles, turning farm outputs into value-added products for local markets, reducing waste, and extending shelf life. His mentorship of women, youth, and fellow farmers ensures the transfer of agroecological skills, building local capacity for sustainable food systems. By connecting grassroots ingenuity with science, policy, and investment, Mzee Mukoko’s work offers a compelling model for climate-resilient, inclusive, and regenerative food systems, safeguarding agroecological heritage for future generations.
Comparative Assessment of Gasifier Cookstove Performance on Smallholder Farms in Three Regions in Kenya
A majority of households in sub-Saharan Africa use inefficient biomass stoves in poorly ventilated kitchens, leading to indoor air pollution. Biomass for cooking can be sustainably sourced from agricultural residues such as prunings from agroforestry. This study assessed biochar-producing gasifier cookstove performance among 150 households in Embu, Kwale, and Siaya Counties through household surveys and participatory cooking tests with 75 households. With the gasifier, carbon monoxide (CO) concentrations were lower in Embu (5.1 ppm), while carbon dioxide (CO2) and fine particulate matter (PM2.5) were lower in Kwale, at 588 ppm and 136 μg/m3, respectively. Compared to the three-stone open fire, reductions in CO and PM2.5 concentrations were highest in Embu, at 82% and 97%, respectively. The biomass-to-char conversion efficiency with the gasifier was 17–18%. If households consider the produced char as a soil amendment, they could save 24–43% of fuel compared to the three-stone open fire; if the char is seen as fuel, the potential savings are 42–65%. Significant differences between the three sites were observed with the gasifier for gross and net fuel use, and for concentrations of PM2.5 and CO2. Gasifier uptake can reduce the need for fuel collection and indoor air pollution, with a positive impact on both the environment and human wellbeing.
Biochar and Moringa seed proteins for greywater treatment
This policy brief presents key findings and advice on the use of biochar and Moringa oleifera (MO) seed proteins for household greywater treatment. The research aimed to evaluate the effectiveness of a low-cost innovation for greywater treatment that addresses challenges regarding access to clean water, women’s and children’s water burdens and opportunities for recovering and reusing of greywater.
Factors influencing the adoption of biochar-producing gasifier cookstoves by households in rural Kenya
Fuel wood is the main source of cooking and heating energy in developing countries. However, it is combusted in inefficient cookstoves, leading to more fuel use and human health problems resulting from exposure to smoke. Thus new, efficient cooking systems that can address some of these problems are required. This study examined gasifier cookstove use in Kwale County, Kenya, and factors influencing adoption. Gasifier stoves were issued for free to 50 households, which were surveyed after 2–3 months of use. The results showed that the stove was used by 96% of the households at varying frequencies, 40% of them used it almost every day with 4% switching to only using the new stove. All the users appreciated it because it saved fuel, produced less smoke, and produced charcoal to use for either cooking or soil amendment. Compared with the traditional three-stone open fire, the gasifier stove was reported to be easier to clean (98% of respondents), easier to adjust the heat (88%), easier to handle (58%), caused less exposure to heat (96%) and was cleaner for pots and the kitchen (98%). Another reported benefit of the gasifier stove was that it needed no tending (i.e., adjusting wood and blowing to keep the flames burning). The gasifier stove was mainly used to cook foods that required a short cooking time and many preferred to use it to cook dinner. However, the households encountered some challenges with using the gasifier stoves. For example, fuel preparation, reloading, and lighting were reported as challenges by 42%, 77% and 19%, respectively, of the 83% of households who reported challenges. These challenges could be overcome by improving stove design and by devising innovative ways of cutting fuel into small pieces.
Ammonia and nitrous oxide emissions from a field Ultisol amended with tithonia green manure, urea, and biochar
Short-term mitigation of ammonia (NH3) and nitrous oxide (N2O) emissions by biochar soil amendments has been reported, but limited knowledge of the mechanisms, particularly those associated with long term changes, remain relatively unknown. In order to investigate potential mechanisms and residual effect of biochar on NH3 and N2O emission, a 3-year field trial was set up on an Ultisol in western Kenya with a three-replicate full factorial treatment structure. The factors investigated include the following: biochar (from eucalyptus wood, pyrolyzed at 550 °C, applied once before the start of the experiment at either 0 or 2.5 t ha−1); tithonia green manure applied at the start of each season at either 0, 2.5, or 5.0 t ha−1; mineral nitrogen (N) (as urea applied each season at either 0 or 120 kg N ha−1). NH3 as well as N2O emission and water-filled pore space (WFPS) were monitored throughout the 3 years. In the third year, soil mineral nitrogen (exchangeable NH4+ and NO3−) contents were measured. Biochar reduced cumulative emissions of NH3 and N2O by 47 ± 5 and 22% ± 3, respectively, over the 3 years. Over the 3 years, the effect size of biochar was reduced by 53 and 59% for NH3 and N2O, respectively, indicating that the residual effect of biochar on NH3 and N2O persists at least up to 3 years under field conditions. Tithonia and urea additions increased both gas emissions by 13–68% compared to the control. Combination of the three amendments reduced cumulative NH3 emissions by 18 ± 3%, but had no effect on cumulative N2O. Our results show that biochar can influence emissions of NH3 and N2O longer than most previous studies have reported but is not explained by N dynamics. Other mechanisms such as direct interactions with oxidized biochar surfaces could be more likely to account for the residual effect of biochar on NH3 and N2O in agricultural soils.
Earthworms regulate ability of biochar to mitigate CO2 and N2O emissions from a tropical soil
Soils account for >80% and 20% of the total agricultural N2O and CO2 emissions respectively. Soil management activities that target improved soil health, such as enhancing earthworm activity, may also stimulate further emissions of CO2 and N2O. One recommended strategy for mitigating these soil emissions is biochar amendment. However greater clarity on the interaction between earthworm activity and biochar, and subsequent impact on CO2 and N2O are needed to evaluate the environmental impacts of management practice. We measured N2O and CO2 emissions from a kaolinitic Acrisol in the presence or absence of earthworms, with and without application of two different biochars in a microcosm study. The two biochars were derived from indigenous trees; Zanthoxylum gilletii and Croton megalocarpus, and were tested at three application rates of 5 Mg ha−1, 10 Mg ha−1 and 25 Mg ha−1. Emissions of CO2 and N2O increased by 26% and 72% respectively in the presence of earthworms. In microcosms with biochar and earthworms however, emissions depended on type of biochar and rate of application. With C. megalocarpus, CO2 emission increased with increasing rates of biochar application with 25 Mg ha−1 resulting in higher CO2 fluxes compared to no-biochar control (p = 0.002), while no change was observed with Z. gilletii at the same rate. Nitrous oxide emissions were suppressed at 25 Mg ha−1 for both C. megalocarpus (p = 0.009) and Z. gilletii (p = 0.011). Reduction in N2O flux was however not consistent across biochar types. No change in N2O was observed with 5 Mg ha−1 and 10 Mg ha−1of C. megalocarpus. Biochar from Z. gilletii at 5 Mg ha−1 however led to increase in N2O emissions (p < 0.001). Our findings suggest that earthworms may moderate the effect of biochar, with suppression of N2O emissions occurring at only high biochar application rates, which may occur at the cost of increasing CO2 emissions. These findings contrast with biochar suppressing effect on N2O emissions even at moderate biochar rates of (10 Mg ha−1) when in absence of earthworms, an outcome typical of many laboratory experiments. These findings highlight new interactions among application rate, source of biochar (and hence properties) and earthworms.
Life cycle assessment: Biochar as a greenhouse gas sink?
[No abstract available]