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)

International Centre for Research in Agroforestry (ICRAF) - Kenya

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

KARI Headquarters (KARI Headquarters) - Kenya

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

Jomo Kenyatta University (Jomo Kenyatta University) - Kenya

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

Quand les données ont-elles été compilées (sur le terrain)?

08/02/2011

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

Oui

2.1 Courte description de la Technologie

Définition de la Technologie:

Stonelines are constructed along the contours to slow down the speed of runoff, filter the soil and enhance water infiltration.

2.2 Description détaillée de la Technologie

Description:

In Kenya stone lines are mostly practiced in areas that receive 200-750 mm of annual rainfall with a spacing of 15-30 m between them. They are particularly common in areas where rocks are readily available, such as Mbeere, Laikipia, Baringo, Mwingi, Kitui and Tharaka. Since the stonelines are permeable they do not pond runoff water but instead, they slow down the speed, filter it and spread the water over the field, thus enhancing water infiltration and reducing soil erosion. They are built in series running along the slope. In addition, the stone barrier blocks and settles down the sediments transported from the upper slopes.

Purpose of the Technology: They are often used to rehabilitate eroded and abandoned land. The advantages of stonelines include; slowing down the runoff thereby increasing infiltration and soil moisture. They also induce a natural process of terracing, reducing erosion and rehabilitation of eroded lands by trapping silt. They are easy to design and construct and since the stone line structure is permeable there is no need for construction of spillways to drain the excess runoff water. When it rains, the soil builds up on the upslope side of the stonelines and over time a natural terrace is formed.

Establishment / maintenance activities and inputs: The stonelines are spaced 15-30 m apart, a shorter distance being used for the steeper slopes. Stonelines are normally suitable on gentle slopes. Slopes above 35% should be avoided. They are established in the following manner: first, the contour line are marked out with the help of a tube level or line levels. In this region here, it is done with the help of the frontline agricultural extension officers. Secondly, a shallow foundation trench is dug across the slope (5-10 cm to 30 cm deep) using basic farm equipments (jembes or hoes). As shown on the above photographs, the larger stones are put on the down slope side of the trench while the smaller stones are used to build the rest of the bund. The smallest stones are used to fill the gaps and increase the heights of the bunds up to the desired level. Farmers plant fruit trees (pawpaws) as show in the photograph above on the upper part. The trees utilises the moisture and rich sediments deposited on the upper part. The stonelines can be reinforced with earth, or crop residues to make them more stable. Maintenance of stonelines is done by repairing the already damaged /fallen stoneline that may have been knocked down or disarranged by livestock or by human beings. In this case animal access needs to be limited and/or the bund should be laid out in a way that allows the animals to pass through.

Natural / human environment: In the lower Mbeere South District where the stoneline technologies is largely practiced, unless there are stones in the individual farms, it might be difficult to import stones from other farms as the exercise can be labor intensive. In this catchment, the Ministry of Agriculture through the front line extension officers has taken a lead role in encouraging farmers to adopt the technology especially the farms which have many stones. Most of the farmers who have implemented this technology in the Lower Mbeere South District learn from the ones who are already practicing through field days or individual initiatives.

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

Si l'année précise est inconnue, indiquez la date approximative: :

• il y a entre 10-50 ans

2.7 Introduction de la Technologie

Spécifiez comment la Technologie a été introduite: :

• grâce à l'innovation d'exploitants des terres

Commentaires (type de projet, etc.) :

The land had too many stones which inhibited operations. By removing the stones, the farmer placed them in line along the contour.

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

• réduire, prévenir, restaurer les terres dégradées

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

Commentaires:

Major land use problems (compiler’s opinion): Limited cultivation land due to hindrances that are brought about by the scattered stones on the land's surface.

Major land use problems (land users’ perception): Soil erosion because of lack of soil and water conservation structures that leads to low land productivity.

Future (final) land use (after implementation of SLM Technology): Cropland: Ca: Annual cropping

Si l'utilisation des terres a changé en raison de la mise en œuvre de la Technologie, indiquez l'utilisation des terres avant la mise en œuvre de la Technologie:

Cropland: Ct: Tree and shrub cropping

3.3 Informations complémentaires sur l'utilisation des terres

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

• pluvial

Nombre de période de croissance par an: :

• 2

Précisez:

Longest growing period in days: 90 Longest growing period from month to month: March-May Second longest growing period in days: 90 Second longest growing period from month to month: October - December

3.4 Groupe de GDT auquel appartient la Technologie

• dérivation et drainage de l'eau

3.5 Diffusion de la Technologie

Spécifiez la diffusion de la Technologie:

• répartie uniformément sur une zone

Si la Technologie est uniformément répartie sur une zone, indiquez la superficie couverte approximative:

• < 0,1 km2 (10 ha)

Commentaires:

Not many farmers are practicing stonelines, the farmers who are practicing are copying from some successful farmers within their neighborhood. They also corroborate with the local agricultural extension officers from the Ministry of Agriculture (MoA) to show them how to construct the stonelines along the contours.

3.6 Mesures de GDT constituant la Technologie

3.7 Principaux types de dégradation des terres traités par la Technologie

Commentaires:

Main type of degradation addressed: Wt: loss of topsoil / surface erosion

Main causes of degradation: soil management, Heavy / extreme rainfall (intensity/amounts), poverty / wealth, labour availability (Construction of the technology is labour intensive)

Secondary causes of degradation: deforestation / removal of natural vegetation (incl. forest fires)

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:

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

Commentaires:

Secondary goals: mitigation / reduction of land degradation

4.1 Dessin technique de la Technologie

4.2 Spécification/ explications techniques du dessin technique

This is a technical drawing representing a cross-section view of how the stonelines are constructed by the emerging farmers in the lower Mbeere South District.

First, a small trench is dug along an established contour line, the farmer starts arranging the stones with reference to their sizes. The bigger ones are arranged on the lower side and the small ones on the upper side as shown on the technical drawing.

By so doing, the eroded soils are trapped on the upper side by the small pebbles, allowing the water to pass through at lower speed hence low erosive capacity.

Location: Ntharawe. Lower Mbeere South District

Date: 2011-08-02

Technical knowledge required for field staff / advisors: moderate (In order to implement this technology, the farmers contact the front line agricultural extension officer in order to assist in making the contours.)

Technical knowledge required for land users: high (Stone required placement of a certain order. Big stone on the lower side and small stones on the upper side-Vertically)

Main technical functions: water spreading, sediment retention / trapping, sediment harvesting

Secondary technical functions: reduction of slope angle

Bund/ bank: graded
Spacing between structures (m): 15
Height of bunds/banks/others (m): 0.8
Width of bunds/banks/others (m): 1.2
Length of bunds/banks/others (m): 27.6

Slope (which determines the spacing indicated above): 8%

Lateral gradient along the structure: 8%

4.3 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

autre/ monnaie nationale (précisez):

Kshs

Indiquer le taux de change du dollars en monnaie locale (si pertinent): 1 USD= :

80,0

4.4 Activités de mise en place/ d'établissement

	Activité	Type de mesures	Calendrier
1.	Establish a contour line and dig up a trench upon which the stones will be arranged	Structurel	yearly
2.	stones are collected and arranged along the established trench. The big boulders are reduced to the required sizes by the use of mattocks	Structurel	once
3.	The big stones are arranged on the lower side and the rest follows with respect to their sizes on the upper side	Structurel
4.	This formation is done per meter length. Mostly is charged 150Kshs per meter.	Structurel

4.5 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	Establish a contour line	Persons/day	0,5	3,76	1,88	100,0
Main d'œuvre	Reduce stone size	Persons/day	0,5	3,76	1,88	100,0
Main d'œuvre	Arranging stones	Persons/day	0,5	3,76	1,88	100,0
Equipements	Mattock	pieces	1,0	18,75	18,75	100,0
Equipements	Wheelbarrow	pieces	1,0	20,0	20,0	100,0
Matériaux de construction	Stone	no	1,0	1,88	1,88	100,0
Coût total de mise en place de la Technologie					46,27

Commentaires:

Duration of establishment phase: 1 month(s)

4.6 Activités d'entretien/ récurrentes

	Activité	Type de mesures	Calendrier/ fréquence
1.	Repair/Rearrange stone on stone line after a rainy seasons or when people and animals have destroyed the stone line.	Structurel	yearly during dry season

4.7 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
Main d'œuvre	Repair/Rearrange stone	mandays/acre	14,0	2,5	35,0	100,0
Coût total d'entretien de la Technologie					35,0

Commentaires:

Machinery/ tools: A wheel barrow (for carrying) and mattocks (for breaking) may be used

The cost applies for the year 2011 and was calculated per metre square, metre length, metre height and metre width.

4.8 Facteurs les plus importants affectant les coûts

Décrivez les facteurs les plus importants affectant les coûts :

The system is labour intensive and hence will affect the cost of constructing the stonelines. However, availability of farm equipments like wheelbarrows, mattocks or oxen will help reduce the total cost and time required for construction and maintaining the stonelines. On steep slopes, the spacing between the lines is small as compared to a relatively gentle slope.

5.1 Climat

5.2 Topographie

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.

Soil texture: With a lot of stones

Soil fertility is medium

Soil drainage / infiltration is medium

Soil water storage capacity is medium

5.4 Disponibilité et qualité de l'eau

Commentaires et précisions supplémentaires sur la qualité et la quantité d'eau:

Availability of surface water: The rivers are seasonal, water availability is from river beds if not during the rainy seasons

5.5 Biodiversité

5.6 Caractéristiques des exploitants des terres appliquant la Technologie

Indiquez toute autre caractéristique pertinente des exploitants des terres:

Land users applying the Technology are mainly common / average land users

Population density: 10-50 persons/km2


Annual population growth: < 0.5%

80% of the land users are poor.

5.7 Superficie moyenne des terres détenues ou louées par les exploitants appliquant la Technologie

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

Propriété foncière:

• individu, avec titre de propriété

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

Autres impacts socio-économiques

Impacts socioculturels

Impacts écologiques

Sols

Biodiversité: végétale, animale

Réduction des risques de catastrophe et des risques climatiques

6.2 Impacts hors site que la Technologie a montrés

6.3 Exposition et sensibilité de la Technologie aux changements progressifs et aux évènements extrêmes/catastrophes liés au climat (telles que perçues par les exploitants des terres)

Changements climatiques progressifs

Changements climatiques progressifs

	Saison	Type de changements/ extrêmes climatiques	Comment la Technologie fait-elle face à cela?
températures annuelles		augmente	bien

Extrêmes climatiques (catastrophes)

Catastrophes météorologiques

	Comment la Technologie fait-elle face à cela?
pluie torrentielle locale	pas bien
tempête de vent locale	bien

Catastrophes climatiques

	Comment la Technologie fait-elle face à cela?
sécheresse	bien

Catastrophes hydrologiques

	Comment la Technologie fait-elle face à cela?
inondation générale (rivière)	pas bien

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)?

6.5 Adoption de la Technologie

Commentaires:

There is a moderate trend towards spontaneous adoption of the Technology

Comments on adoption trend: The technology is mainly practiced on the farms with stones even though the farmers admit that the task of construction is labour intensive. However, these not withstanding, the farmers do acknowledge that the technology is beneficial since they can see the results of yields from the ones who are already practicing.

6.7 Points forts/ avantages/ possibilités de la Technologie

Points forts/ avantages/ possibilités du point de vue de l'exploitant des terres
By concentrating the stones along a contour, the farmer is able to make use of the land which otherwise is not possible if the stones are scatered. How can they be sustained / enhanced? Farmers should be encouraged to learn from one another but they should also seek advice from extension officers in making the contours.
The cost of replacement of farm equipments (jembes, forks and pangas) is reduced since they aren't broken by stones during land preparation.

Points forts/ avantages/ possibilités du point de vue du compilateur ou d'une autre personne ressource clé
The stones for constructing the technology are readily available in most of the farms. How can they be sustained / enhanced? Encouraging farmers to use the available stones to put up the technology.
Stoneline technology prevents soil loss due to erosion. How can they be sustained / enhanced? Modification of the technology to allow more infiltration.
No high level technical knowledge is required for construction of stoneline technology. How can they be sustained / enhanced? More farmers should be encouraged to adopt the technology since they dont need a high level of technical knowledge.
Stone lines technology can be modified to prevent soil and water from running off on the side of stone line ridge. How can they be sustained / enhanced? Construction of side ridges.

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?
Contour profiling is challenging.	Assistance from the front line agricultural extension officers.

Faiblesses/ inconvénients/ risques du point de vue du compilateur ou d'une autre personne ressource clé	Comment peuvent-ils être surmontés?
Labour intensive.	When constructing, always move the stones downslope by gravity instead of moving upwards i.e. start from the contours from the upper side
The technology only allows the soil to deposit on the upper side of the stoneline but water passes through.	Proper arrangement of the stones should be enhanced basing on their sizes.
Increased habitats for snakes and other dangerous creatures like scorpions that hide on the stonelines.	Where there creatures are prone, the farmers should be careful.

7.2 Références des publications disponibles

Titre, auteur, année, ISBN:

Thomas, D.B. (eds) 1997. Soil and Water Conservation Manual for Kenya. Soil and Water Conservation Branch. Ministry of Agriculture, Livestock Development and Marketing. 210 p.

Titre, auteur, année, ISBN:

Critchley W and Seigert K (1991) Water Harvesting. FAO