1.2 Contact details of resource persons and institutions involved in the assessment and documentation of the Technology

Name of project which facilitated the documentation/ evaluation of the Technology (if relevant)

Programme d’Appui à l’agriculture Productive (GIZ / PROMAP)

Name of project which facilitated the documentation/ evaluation of the Technology (if relevant)

Manual of Good Practices in Small Scale Irrigation in the Sahel (GIZ )

Name of the institution(s) which facilitated the documentation/ evaluation of the Technology (if relevant)

Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) - Germany

Name of the institution(s) which facilitated the documentation/ evaluation of the Technology (if relevant)

Misereor - Germany

1.3 Conditions regarding the use of data documented through WOCAT

The compiler and key resource person(s) accept the conditions regarding the use of data documented through WOCAT:

Yes

2.1 Short description of the Technology

Definition of the Technology:

Contour stone bunds are erosion control structures and improve water retention and infiltration into the soil, resulting in an increased harvest.

2.2 Detailed description of the Technology

Description:

Contour stone bunds are erosion control structures built with quarry rock or stones in series of two or three. They are constructed in lines along the natural contour of the land after 10-15 cm of the soil has been removed from the line where they are to be built. They should be built to a height of 20-30 cm from the ground and spaced 20 to 50 m apart depending on the inclination of the terrain.
The best results are achieved when contour stone bunds are used in combination with biological measures (planting of grass, trees and hedges) and the use of organic fertiliser and mulching.

Purpose of the Technology: Contour stone bunds protect the land against sheet erosion caused by runoff. They form a barrier that slows down runoff and spreads it more evenly over the land. By slowing the flow of water over the land, it can seep into the soil and prevents the loss of rainwater. The bunds also act as a filter, trapping fine waterborne particles of soil and manure, resulting in a build-up of sediment and the formation of terraces. The seeds of grasses and shrubs are also trapped by the bunds, favouring the establishment of natural vegetation along the structure. This further stabilises the soil and the bunds and contributes to conserving the biodiversity of plants and small wild animals (monitor lizards, birds, snakes and other reptiles). If good vegetation cover is developed on the stone bunds, they also lower soil temperature and provide protection against wind erosion. Excess water filters through the bunds and infiltrates into the soil. When rainfall is erratic, the stone bunds contribute to conserving more moisture in the soil for longer, which helps to alleviate water stress during dry spells. There is evidence that bunds that have been in place for over 15 years have positive effects on yields.

Establishment / maintenance activities and inputs: A minimum amount of upkeep is required, which essentially involves replacing stones dislodged by animals or water flow. The lifespan of a stone bund is over 20 years.
In order to optimise the positive effects of stone bunds, it is important to ensure that they are constructed closely following the natural contour of the land and in accordance with the established technical standards.
The means of transport required depends on the proximity of a quarry or a supply of stones (cart or lorry).

Natural / human environment: This technique is designed for cropland, but can also be used on forest/rangeland. It is suitable for areas in the Sahel and the Sudan with rainfall ranging between 300 and 900 mm/year and low-to-medium gradient terrain.
When rainfall is high, they protect the land in the event of heavy rain, a phenomenon that tends to increase with climate change.

2.3 Photos of the Technology

2.5 Country/ region/ locations where the Technology has been applied and which are covered by this assessment

2.6 Date of implementation

If precise year is not known, indicate approximate date:

• 10-50 years ago

2.7 Introduction of the Technology

Specify how the Technology was introduced:

• through projects/ external interventions

Comments (type of project, etc.):

Known as traditional method in some areas. Improved and up-scaled as part of numerous projects in many semi-arid countries. German Developmenmt Cooperation has used the technology from the 1980s onwards to combat desertification and improve natural resource management e.g. PDRT (Projet de développement rural de Tahoua - Tahoua Rural Development Project), PASP (Projet de protection intégrée des ressources agro-sylvo-pastorales Tillabéri-Nord - Project for the Integrated Protection of Agricultural, Forest and Rangeland Resources in Tillabéri-Nord) and several other projects of GIZ/KfW and other donors.

3.1 Main purpose(s) of the Technology

• reduce, prevent, restore land degradation

3.2 Current land use type(s) where the Technology is applied

Land use mixed within the same land unit:

Yes

Specify mixed land use (crops/ grazing/ trees):

• Agro-silvopastoralism

Comments:

major cash crop: Ground nut
major food crop: Millet
other: Sorghum, cow pea and mangoes

Major land use problems (compiler’s opinion): surface runoff, erosion by water and wind, fertility decline,

Nomadism: Yes

Semi-nomadism / pastoralism: Yes

Cut-and-carry/ zero grazing: Yes

Improved pasture: Yes

Other grazingland: agropastoralism

Selective felling of (semi-) natural forests: Yes

Forest products and services: timber, fuelwood, fruits and nuts, grazing / browsing, other forest products / uses (honey, medical, etc.)

Type of cropping system and major crops comments: farmers are mainly agropastoralists with some communities specialised on pure pastoralism

Constraints of common grazing land

Constraints of forested government-owned land or commons

Livestock density: 1-10 LU /km2

3.4 Water supply

Water supply for the land on which the Technology is applied:

• rainfed

Comments:

Water supply: Also mixed rainfed - irrigated and post-flooding

3.5 SLM group to which the Technology belongs

• cross-slope measure

3.6 SLM measures comprising the Technology

3.7 Main types of land degradation addressed by the Technology

Comments:

Secondary types of degradation addressed: Et: loss of topsoil

Main causes of degradation: soil management (Unadapted landuse methods, reduced or abandoned fallow periods), crop management (annual, perennial, tree/shrub) (Neglect of fallow periods and crop rotation), droughts (due to heat waves and unreliable rainfall), population pressure (rapidly growing population increasing pressure on land), land tenure (insecure access to land and collectively managed communal land), poverty / wealth (very poor population)

Secondary causes of degradation: deforestation / removal of natural vegetation (incl. forest fires) (deforestation through overgrazing and fire wood collection), over-exploitation of vegetation for domestic use (firewood collection), overgrazing (cattle, sheep and goats), change in temperature (Climate change: heat waves), change of seasonal rainfall (more variable onset of rain), Heavy / extreme rainfall (intensity/amounts) (more variable and intensive rains), wind storms / dust storms (frequent storms), floods (due to intensive rain storms), labour availability (some migration of men to nearby cities), education, access to knowledge and support services (high level of illiteracy)

3.8 Prevention, reduction, or restoration of land degradation

Specify the goal of the Technology with regard to land degradation:

• restore/ rehabilitate severely degraded land

Comments:

Secondary goals: prevention of land degradation, mitigation / reduction of land degradation

4.1 Technical drawing of the Technology

4.2 General information regarding the calculation of inputs and costs

Specify currency used for cost calculations:

• USD

4.3 Establishment activities

	Activity	Timing (season)
1.	Levelling and marking out the contour lines
2.	collecting stones and loading them onto carts
3.	transporting the stones by cart
4.	constructing the bunds
5.	applying manure

4.4 Costs and inputs needed for establishment

	Specify input	Unit	Quantity	Costs per Unit	Total costs per input	% of costs borne by land users
Labour	Levelling and construction of bunds	ha	1.0	19.32	19.32
Equipment	Tools	ha	1.0	1.95	1.95
Other	Transport of stones	ha	1.0	15.07	15.07
Total costs for establishment of the Technology					36.34
Total costs for establishment of the Technology in USD					36.34

4.5 Maintenance/ recurrent activities

	Activity	Timing/ frequency
1.	Replacing stones dislodged by animals or water flow

4.7 Most important factors affecting the costs

Describe the most determinate factors affecting the costs:

The exact cost per hectare of constructing stone bunds depends on the distance of the site from the quarry, the size of the quarry, the inclination of the terrain, which determines the spacing between the stone bunds, and the actual amount of stones transported in each lorryload. The prices below are provided as a guide.
Supply of quarry rock/stones: 24 m3 per 400 m of bund
Labour: 30 man-days per ha
• levelling and marking out the contour lines: 1 man-day
• collecting stones and loading them onto carts:
10 man-days
• transporting the stones by cart: 10 man-days
• constructing the bunds: 9 man-days
• applying manure.
Transportation by cart:
• 20 cartloads of stones
• 20 cartloads of manure (if used).
Transportation by lorry:
• 6 lorryloads (skip loader – 4.5 m3 per load).
Other costs: equipment (pickaxes, shovels, wheelbarrows, water-tube level, etc.).

5.1 Climate

5.2 Topography

Comments and further specifications on topography:

Landforms: Also footslopes and valley floors

Altitudinal zone: 200 m a.s.l.

5.3 Soils

If available, attach full soil description or specify the available information, e.g. soil type, soil PH/ acidity, Cation Exchange Capacity, nitrogen, salinity etc.

Soil texture (topsoil): Fine to medium (sandy to clayey loams)

5.4 Water availability and quality

Comments and further specifications on water quality and quantity:

Ground water table: > 10 m

Availability of surface water: Surface runoff generated by limited but intense rainfalls

5.5 Biodiversity

5.6 Characteristics of land users applying the Technology

Indicate other relevant characteristics of the land users:

Population density: 10-50 persons/km2

Annual population growth: 3% - 4%

(mostly poor households below poverty line).

Off-farm income specification: men migrate temporarily or permanently to cities for off-farm income, women and men seasonally carry out paid farm work

Market orientation of production system: Most households crop for subsistence (mainly for small agropastoralists) and surplus is sold on market (medium agropastoralists). Commercial markets: some vegetable growing and pastoralists.

Level of mechanization: Ox and donkey used for animal traction

5.7 Average area of land used by land users applying the Technology

5.8 Land ownership, land use rights, and water use rights

Land ownership:

• state
• communal/ village

Land use rights:

• communal (organized)
• individual

Comments:

traditional land use rights prevail. On fields individual land use rights, communal rights on pasture and forest land (collection of wood and other products (fruits, medicinal plants))

Land ownership: Also individual not titled

5.9 Access to services and infrastructure

6.1 On-site impacts the Technology has shown

Socio-economic impacts

Production

Water availability and quality

Income and costs

Socio-cultural impacts

Ecological impacts

Water cycle/ runoff

Soil

Biodiversity: vegetation, animals

Climate and disaster risk reduction

Other ecological impacts

6.2 Off-site impacts the Technology has shown

6.3 Exposure and sensitivity of the Technology to gradual climate change and climate-related extremes/ disasters (as perceived by land users)

Gradual climate change

Gradual climate change

	Season	increase or decrease	How does the Technology cope with it?
annual temperature		increase	well

Climate-related extremes (disasters)

Meteorological disasters

	How does the Technology cope with it?
local rainstorm	not well
local windstorm	well

Climatological disasters

	How does the Technology cope with it?
drought	well

Hydrological disasters

	How does the Technology cope with it?
general (river) flood	not well

Other climate-related consequences

Other climate-related consequences

	How does the Technology cope with it?
reduced growing period	not known

6.4 Cost-benefit analysis

How do the benefits compare with the establishment costs (from land users’ perspective)?

How do the benefits compare with the maintenance/ recurrent costs (from land users' perspective)?

6.5 Adoption of the Technology

Of all those who have adopted the Technology, how many did so spontaneously, i.e. without receiving any material incentives/ payments?

• 51-90%

Comments:

Comments on acceptance with external material support: While in emergency programs erosion control structures are mostly implemented through cash/food for work this is not the case in natural resource programs. As concerns German Development Cooperation, cash/food for work has been used during the 80ies and 90ies to implement stone bunds. Thereafter most programs switched to a voluntary approach where only Tools and transport were provided but all labour has been provided by the beneficiaries without payment.

80% of land user families have adopted the Technology without any external material support

There is a little trend towards spontaneous adoption of the Technology

Comments on adoption trend: The success of this measure and implementation on a wide scale depend to a large extent on whether grants are available to cover the cost of transporting the stones required to the site, good community organisation and the capacity of the community to mobilise the necessary labour, the contribution required from the farmers.
The farmers’ commitment to implementing the measure largely depends on whether they are allowed to choose the sites to be improved in their area. Forcing them to begin the improvement work upstream, as dictated by the traditional watershed development approach, has often proved counterproductive. Most communities prefer to improve individual plots first in order to achieve immediate effects on crop production and leave the treatment of forest/ rangeland areas as a second step.

6.7 Strengths/ advantages/ opportunities of the Technology

Strengths/ advantages/ opportunities in the compiler’s or other key resource person’s view
There is evidence that bunds that have been in place for over 15 years have positive effects on yields. Grain yields increase by more than 40% for millet up to 15 years after the bunds were established, and there is no evidence to suggest that yields decline with time. This can be explained by improved soil structure, which increases infiltration, even after the bunds are completely silted up.
The lifespan of a stone bund is over 20 years. There is a progressive build-up of sediment behind the bunds, resulting in the formation of terraces. Although the capacity of the bunds to retain water declines as the sediment builds up, soil infiltration capacity increases, thanks to improved soil structure, and the slope becomes gentler thanks to the terracing effect. How can they be sustained / enhanced? Farmers can maintain water retention capacity by raising the height of the existing bunds. In some places, farmers take the stones from the original bunds when a ridge of vegetation has been established and use them to form new bunds between the old ones.
The decrease in surface runoff in the treated area reduces the flow of floodwater and the amount of sediment carried by the water downstream, thereby protecting the fertile land in the valley bottoms from siltation and gully erosion. How can they be sustained / enhanced? In order to optimise the positive effects of stone bunds, it is important to ensure that they are constructed closely following the natural contour of the land and in accordance with the established technical standards.
In dry years, while unimproved land produces nothing, land protected by stone bunds can still produce a harvest. How can they be sustained / enhanced? When stone bunds are used in combination with zai planting pits, sorghum yields can increase by 114-124%. When used in conjunction with the application of the right amount of organic fertiliser, sorghum yields can be doubled.
Higher crop production improves household food security in proportion to the area of a farm improved with bunds. Under the PASP in Niger, an average of 16% of the area of a farm was improved with stone bunds, resulting in an increase of between 8% and 33% in annual output with no other additional measures.

6.8 Weaknesses/ disadvantages/ risks of the Technology and ways of overcoming them

Weaknesses/ disadvantages/ risks in the compiler’s or other key resource person’s view	How can they be overcome?
In wet years, the bunds may cause waterlogging in some parts of the field, which can adversely affect some crops.	If this happens, farmers must open up a gap in the bunds to drain off the water.

7.1 Methods/ sources of information

7.3 Links to relevant online information

Title/ description:

Good Practices in Soil and Water Conservation. A contribution to adaptation and farmers resilience towards climate change in the Sahel. Published by GIZ in 2012.

URL:

http://agriwaterpedia.info/wiki/Main_Page