1.2 Coordonnées des personnes-ressources et des institutions impliquées dans l'évaluation et la documentation de la Technologie

Nom du ou des institutions qui ont facilité la documentation/ l'évaluation de la Technologie (si pertinent)

Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH (GIZ) - Allemagne

1.3 Conditions relatives à l'utilisation par WOCAT des données documentées

Le compilateur et la(les) personne(s) ressource(s) acceptent les conditions relatives à l'utilisation par WOCAT des données documentées:

Oui

1.4 Déclaration sur la durabilité de la Technologie décrite

Est-ce que la Technologie décrite ici pose problème par rapport à la dégradation des terres, de telle sorte qu'elle ne peut pas être déclarée comme étant une technologie de gestion durable des terres?

Non

2.1 Courte description de la Technologie

Définition de la Technologie:

Application of biochar to soils in the tropics / sub-tropics improves their ability to store and supply nutrients and water for crop growth, thereby enhancing yields and food security. At the same time, biochar holds carbon in soils for extended time periods, which makes it an agricultural practice that contributes to climate change mitigation.

2.2 Description détaillée de la Technologie

Description:

Biochar is carbonised organic material that is produced through pyrolysis, that is thermal conversion under low or no oxygen. The biochar is used as an amendment to farmland for ameliorating soil properties. Owing to the great number of micropores and charges on biochar, its application to soil boosts water and nutrient storage, and their delivery to crops. Biochar also helps neutralise acidity in soils, replacing the need for lime. All these positive effects make it ideally suited for acid, nutrient-poor soils in tropical/ sub-tropical regions. Even at low rates of 1 or 2 tonnes per hectare, biochar significantly increases crop production. Biochar hardly decomposes in soils, causing positive effects to last for several years without repeat application. This also provides very stable carbon storage on farms which helps mitigate climate change. Its stability also allows farmers to gradually add biochar to the entire farm, thereby increasing their food self-sufficiency and incomes.
Biochar itself is not a fertilizer, but a soil rejuvenating agent. Therefore, farmers must apply essential nutrients through synthetic or organic inputs to reap the full yield potential and maintain soil fertility. Yet, when biochar is combined with fertilizers, about 40% - 70% nitrogen and phosphorus can be saved over multiple seasons while maintaining the same productivity. Biochar is a promising solution to address low response of crops to fertilizer addition in tropical soils and to alleviate the impact of input price hikes and supply disruptions.
In the study presented here, farmers produced biochar as a residue from small gasifier stoves during daily cooking. These systems are highly energy efficient and reduce the consumption of firewood while improving indoor air quality, which, alongside crop yield gains from biochar, is perceived positively by farmers. The specific design of gasifier stoves requires them to be well-packed with appropriately sized tree prunings or maize stems. For larger meals it requires a refill, which users find less convenient than their traditional open combustion fires. Life-cycle assessment shows that households significantly reduce greenhouse gas emissions with the gasifier stoves when biochar is applied to the farm. For the field trials with maize and kale in this study, farmers applied their usual rates of inorganic fertilizers, animal manure, or a combination of both. Results from this multi-locational participatory assessment showed that maize grain yield increased by 0.2 - 0.7 tonnes per hectare for every tonne of home-made biochar that was added to the field.
One household can produce 300 kg biochar per year by cooking on the gasifier stove. With this amount a biochar dosage of 1.5 t/ha can be realized on an area of 0.2 ha per year. If biochar is not spread evenly, but along seed rows, its effective dosage can be increased. As the gasifier stove can be operated for 2-3 years, it is assumed that the costs of 50 USD, which are needed to purchase one gasifier, are good to equip 1 ha of land with an amount of biochar that results in increased crop yields.

2.3 Photos de la Technologie

2.5 Pays/ région/ lieux où la Technologie a été appliquée et qui sont couverts par cette évaluation

2.6 Date de mise en œuvre de la Technologie

Indiquez l'année de mise en œuvre:

2016

2.7 Introduction de la Technologie

Spécifiez comment la Technologie a été introduite: :

• au cours d'expérimentations / de recherches

Commentaires (type de projet, etc.) :

IITA (International Institute of Tropical Agriculture) started a long-term field trial in 2006, in which crop and soil properties were monitored following one initial biochar application of 100 t/ha. ICRAF investigated the charcoal value chain in Kenya and, among others, promoted cooking stoves which were more efficient than the traditionally used open fires. Those stoves run on pyrolysis, which provides heat for cooking and charcoal as a residual. That charcoal can be used for cooking so that the initial biomass is used more efficiently as an energy source. Or, alternatively, the residual charcoal is used as biochar to improve the farmers' soils.
This combination of cooking and biochar production and application to soils began in 2016 as participatory research.

3.1 Principal(aux) objectif(s) de la Technologie

• améliorer la production
• s'adapter au changement et aux extrêmes climatiques et à leurs impacts
• atténuer le changement climatique et ses impacts
• créer un impact économique positif
• créer un impact social positif

3.2 Type(s) actuel(s) d'utilisation des terres, là où la Technologie est appliquée

Les divers types d'utilisation des terres au sein du même unité de terrain: :

Non

3.3 Est-ce que l’utilisation des terres a changé en raison de la mise en œuvre de la Technologie ?

Est-ce que l’utilisation des terres a changé en raison de la mise en œuvre de la Technologie ?

• Non (Passez à la question 3.4)

3.4 Approvisionnement en eau

Approvisionnement en eau des terres sur lesquelles est appliquée la Technologie:

• pluvial

3.5 Groupe de GDT auquel appartient la Technologie

• gestion intégrée de la fertilité des sols

3.6 Mesures de GDT constituant la Technologie

3.7 Principaux types de dégradation des terres traités par la Technologie

Commentaires:

Biochar increases the cation exchange capacity of soils and enhances the plant availability of phosphorus so that it contributes to soil fertility. Biochar increases the soil pH so that it treats acidification of soils. In the field of soil physical properties, biochar decreases the bulk density of soils and adds pore space to soils so that the infiltration into the soil and the usable field capacity of soils are increased. In this specific case, soil sealing and compaction do not play a role, but biochar can address those soil degradation issues.

3.8 Prévention, réduction de la dégradation ou réhabilitation des terres dégradées

Spécifiez l'objectif de la Technologie au regard de la dégradation des terres:

• réduire la dégradation des terres
• restaurer/ réhabiliter des terres sévèrement dégradées

4.2 Informations générales sur le calcul des intrants et des coûts

Spécifiez la manière dont les coûts et les intrants ont été calculés:

• par entité de la Technologie

Indiquez la monnaie utilisée pour le calcul des coûts:

• dollars américains

4.3 Activités de mise en place/ d'établissement

	Activité	Calendrier des activités (saisonnier)
1.	Biochar production	Year-round while using the gasifier cooking stove.
2.	Mixing biochar into the soil	During the normal time of field preparation for and planting of the next crop
3.	Proceed with normal cropping activities

Commentaires:

This SLM technique adds biochar to the ongoing cropping activities. So, the choice of crops, soil preparation, planting, inputs, and harvest do not change after biochar application. The biochar is sourced from so-called gasifier cooking stoves, which are stoves that perform through pyrolysis. The excess energy of that pyrolysis is used for cooking, while the residual char is applied as biochar to the farmers' field. Char (biochar) is produced during every cooking activity, collected, and finally applied. Most household in the project regions use open three-stone fires for cooking followed by charcoal. Adoption of the gasifier stoves is a shift away from the open fires and charcoal.

4.4 Coûts et intrants nécessaires à la mise en place

	Spécifiez les intrants	Unité	Quantité	Coûts par unité	Coût total par intrant	% des coût supporté par les exploitants des terres
Main d'œuvre	gasifier cooking stove		1,0	50,0	50,0
Coût total de mise en place de la Technologie					50,0
Coût total de mise en place de la Technologie en dollars américains (USD)					50,0

Commentaires:

As costs we only listed the 50 USD per gasifier cooking stove. As the other farm operations do not change, no further costs for plant materials or fertilizers or other were listed, because those inputs do not change solely due to the use of biochar from the gasifier stoves.
One household can produce 300 kg biochar per year by cooking on the gasifier stove. With this amount a biochar dosage of 1.5 t/ha can be realized on an area of 0.2 ha per year. If biochar is not spread evenly, but along seed rows, its effective dosage can be increased. As the gasifier stove can be operated for 2-3 years, it is assumed that the costs of 50 USD are good to equip 1 ha of land with an amount of biochar that results in increased crop yields.

4.5 Activités d'entretien/ récurrentes

	Activité	Calendrier/ fréquence
1.	Replace the gasifier cooking stove	every three years

Commentaires:

Once biochar has been applied into a given soil, it sits there in the soil and does not require further maintenance. The farming activities and their associated labor remain unchanged compared to the the time before biochar application.

4.6 Coûts et intrants nécessaires aux activités d'entretien/ récurrentes (par an)

	Spécifiez les intrants	Unité	Quantité	Coûts par unité	Coût total par intrant	% des coût supporté par les exploitants des terres
Equipements	gasifier cooking stove	1	0,33	50,0	16,5	100,0
Coût total d'entretien de la Technologie					16,5
Coût total d'entretien de la Technologie en dollars américains (USD)					16,5

Commentaires:

The depreciation of the gasifier cooking stove and the need to replace it every three years is included here unde rrecurrent costs.

4.7 Facteurs les plus importants affectant les coûts

Décrivez les facteurs les plus importants affectant les coûts :

Purchase price of the gasifier stove. Opportunity cost for collection and pre-processing of tree prunings and crop residues for the stove.

5.1 Climat

5.2 Topographie

Indiquez si la Technologie est spécifiquement appliquée dans des:

• non pertinent

Commentaires et précisions supplémentaires sur la topographie:

Kwale: 328 m a.s.l.
Embu: 1350 m a.s.l.

5.3 Sols

Si disponible, joignez une description complète du sol ou précisez les informations disponibles, par ex., type de sol, pH/ acidité du sol, capacité d'échange cationique, azote, salinité, etc.

The following information are available for two field plots out of the three counties:
Embu County: pH(H2O) - 5.01, SOC - 2.01%, sand - 21%, clay - 43.5%
Siaya County: pH(H2O) - 5.25, SOC - 1.56%, sand - 22.4%, clay - 60.1%

5.4 Disponibilité et qualité de l'eau

5.6 Caractéristiques des exploitants des terres appliquant la Technologie

Indiquez toute autre caractéristique pertinente des exploitants des terres:

Women and children operate the gasifier stove and therefore produce the biochar. In the field it is mainly men who mix the biochar into the soil and perform other farm operations.

5.7 Superficie moyenne des terres utilisées par les exploitants des terres appliquant la Technologie

5.8 Propriété foncière, droits d’utilisation des terres et de l'eau

Propriété foncière:

• individu, sans titre de propriété
• individu, avec titre de propriété

Droits d’utilisation des terres:

• individuel

Droits d’utilisation de l’eau:

• accès libre (non organisé)

Est-ce que les droits d'utilisation des terres sont fondés sur un système juridique traditionnel?

Oui

5.9 Accès aux services et aux infrastructures

6.1 Impacts sur site que la Technologie a montrés

Impacts socio-économiques

Production

Revenus et coûts

Impacts écologiques

Réduction des risques de catastrophe et des risques climatiques

6.2 Impacts hors site que la Technologie a montrés

6.4 Analyse coûts-bénéfices

Quels sont les bénéfices comparativement aux coûts de mise en place (du point de vue des exploitants des terres)?

Quels sont les bénéfices comparativement aux coûts d'entretien récurrents (du point de vue des exploitants des terres)?

Commentaires:

The main benefits from this SLM technology from the land users' perspective are increased crop yields, reduced need to collect fuel wood, and improved indoor ambient air quality. The latter two benefits materialize immediately, onec the gasifier is used. The crop yields increase during the season that follows the biochar application, which is a short-term benefit. These benefits justify the establishment costs, which in fact are the costs to purchase the gasifier.
On a long-term perspective, the effect to improve the soil, which leads to crop yield increases, remains, because biochar is stable in soils ove rlong time periods. Particularly positive is that there are no maintenence costs to keep the biochar in the soil.

6.5 Adoption de la Technologie

• cas isolés/ expérimentaux

De tous ceux qui ont adopté la Technologie, combien d'entre eux l'ont fait spontanément, à savoir sans recevoir aucune incitation matérielle, ou aucune rémunération? :

• 0-10%

6.6 Adaptation

La Technologie a-t-elle été récemment modifiée pour s'adapter à l'évolution des conditions?

Non

6.7 Points forts/ avantages/ possibilités de la Technologie

Points forts/ avantages/ possibilités du point de vue de l'exploitant des terres
Most land users stated to have observed positive impacts on soil health and improvement of soil fertility. Additionally, about 25% of the land users specifically mentioned that the moisture retention in the soil improved after biochar application. Some land users experienced lower costs for fertilizers.
Most land users found the small top-lit updraft cooking stoves are easy to use, though being more suitable for food with short cooking time. All land users stated that the gasifier cooking stoves were cleaner than the traditional open fires and charcoal stoves, since the gasifiers produced less smoke, less soot, and fewer ashes. Some land users responded even that the gasifiers were less harmful to cooking utensils and food tasted better (less smoky). The gasifier stove was preferred by land users because it takes less fuel and therefore saves time to collect fire wood and household expenditures. This was particularly viewed positively by women. The residual char also can be used as an energy source. Some land users saw sales of charcoal as potential additional income.
In total, the package of using gasifier stoves for cooking and applying the residual biochar to soils was seen as beneficial by most land users, because it saved costs and efforts on the side of cooking and increased crop yields and income.

Points forts/ avantages/ possibilités du point de vue du compilateur ou d'une autre personne ressource clé

Biochar improves soil properties which intensifies crop production. Even a small amount of biochar added to the soil has a long-lasting positive effect on yields. The effect of a one-time biochar application lasts for decades. Therefore, if soils are enriched with biochar by repeatedly adding low quantities, its benefits to land users accumulate over time. Biochar increases the cation exchange capacity, pH, and phosphorus availability of soils, which are key constraints to in many farming systems across tropical Africa. Non-responsive soils are turned into soils that respond to fertilizer application.

6.8 Faiblesses/ inconvénients/ risques de la Technologie et moyens de les surmonter

Faiblesses/ inconvénients/ risques du point de vue de l’exploitant des terres	Comment peuvent-ils être surmontés?
Half of the respondents stated the production of biochar was time consuming due to the process of cutting the feedstock in suitable sizes, as needed for the gasifier stove.	Chopped firewood for the gasifier could become a source of income for youth.

Faiblesses/ inconvénients/ risques du point de vue du compilateur ou d'une autre personne ressource clé	Comment peuvent-ils être surmontés?
Gasifiers may emit more methane than technologically more advanced pyrolysis units.	Improve the gasifier utility with a shift to the latest mobile or decentralized technologies that produce syngas, green hydrogen or electricity that can be used for cooking.
Deploying gasifier and biochar at large scale without regulations poses a risk of unsustainable rates of tree clearing and residue removal.	Follow rules such as EBC and only use on-farm or residual biomass.

7.1 Méthodes/ sources d'information

7.2 Références des publications disponibles

Titre, auteur, année, ISBN:

Biochar from cooking stoves reduces greenhouse gas emissions from smallholder farms in Africa; Sundberg et al., 2020

Disponible à partir d'où? Coût?

https://link.springer.com/article/10.1007/s11027-020-09920-7, open access

Titre, auteur, année, ISBN:

Use of Biochar-Producing Gasifier Cookstove Improves Energy Use Efficiency and Indoor Air Quality in Rural Households; Gitau et al., 2019

Disponible à partir d'où? Coût?

https://www.mdpi.com/1996-1073/12/22/4285, open access

Titre, auteur, année, ISBN:

Implications on Livelihoods and the Environment of Uptake of Gasifier Cook Stoves among Kenya’s Rural Households; Gitau et al., 2019

Disponible à partir d'où? Coût?

https://www.mdpi.com/2076-3417/9/6/1205/pdf, open access

Titre, auteur, année, ISBN:

Factors influencing the adoption of biochar-producing gasifier cookstoves by households in rural Kenya; Gitau et al., 2019

Disponible à partir d'où? Coût?

https://www.sciencedirect.com/science/article/pii/S0973082618308913, open access

Titre, auteur, année, ISBN:

Soils, sinks, and smallholder farmers: Examining the benefits of biochar energy transitions in Kenya; Mahmood et al., 2021

Disponible à partir d'où? Coût?

https://reader.elsevier.com/reader/sd/pii/S2214629621001262?token=D446F30FC8FDAEC80F73AE31BBFEA69E754E2F9EB21A9605CC6D04A2FE0FCD39182848F88AC6D17BF7D12B8EEED7BD9E&originRegion=eu-west-1&originCreation=20210415190025, open access

Titre, auteur, année, ISBN:

Gasifier as a cleaner cooking system in rural Kenya; Njenga et al., 2016

Disponible à partir d'où? Coût?

https://www.sciencedirect.com/science/article/abs/pii/S0959652616000743?via%3Dihub, access at no costs through limited number of institutions

Titre, auteur, année, ISBN:

Biochar addition persistently increased soil fertility and yields in maizesoybean rotations over 10 years in sub-humid regions of Kenya; Kätterer et al., 2019

Disponible à partir d'où? Coût?

https://www.sciencedirect.com/science/article/pii/S0378429018318938?via%3Dihub, open access

Titre, auteur, année, ISBN:

sMaize grain yield responses to realistic biochar application rates on smallholder farms in Kenya, Kätterer et al., 2022

Disponible à partir d'où? Coût?

https://link.springer.com/article/10.1007/s13593-022-00793-5, open access

7.3 Liens vers les informations pertinentes en ligne

Titre/ description:

Biochar stoves for socio-ecological resilience: Lessons from small-scale farms in rural Kenya / Report by ICRAF

URL:

http://apps.worldagroforestry.org/downloads/Publications/PDFS/PB20040.pdf