Contour bunds for crops and forest/rangeland [Niger]
- Compiler: Dieter Nill
- Editor: –
- Reviewers: Alexandra Gavilano, David Streiff, Deborah Niggli
Banquettes agricoles et sylvo-pastorales (French)
technologies_1652 - Niger
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1. General information
1.2 Contact details of resource persons and institutions involved in the assessment and documentation of the Technology
Key resource person(s)
Mamadou Abdou Gaoh Sani
Programme d’Appui à l’agriculture Productive (PROMAP)
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:
1.4 Declaration on sustainability of the described Technology
Is the Technology described here problematic with regard to land degradation, so that it cannot be declared a sustainable land management technology?
2. Description of the SLM Technology
2.1 Short description of the Technology
Definition of the Technology:
Contour bunds, built with earth or stones, increase the amount of water available to crops and vegetation, thus contributing to the restoration of degraded land
2.2 Detailed description of the Technology
A contour bund is a rectangular structure consisting of bunds built with earth or stone or a combination of both, which can be permeable or impermeable. The bottom bund is up to 80 m long, and the wingwalls extend up to 15 m upslope. The contour bunds are built in staggered rows along the natural contour of the land with the open end facing uphill. Patches in the same row are spaced 6 m apart, and the rows are positioned about 25 m apart, depending of the gradient of the slope. Downslope of the structure, a water collection ditch 0.50 m wide and 0.30 m deep is dug. The earth excavated from the ditch is piled up and compacted to construct the main bund. When used for growing crops, a third of the total surface area inside the contour bunds is loosened by subsoiling. The remaining two thirds of the surface are left unworked and serve as a catchment area. This doubles or triples the volume of water available to crops. Trees are planted along the main bund to stabilise the structure.
Contour bunds for forest/rangeland work as contour bunds on cropland (described above), except that the sizing is slightly different. The main bund of patches used for this purpose is up to 100 m long and the rows are spaced up to 30 m apart.
In Niger, contour bunds for forest/rangeland are used to restore land in plateau areas which have been completely degraded and denuded by severe water and wind erosion. Contour bunds for growing crops are recommended for the restoration of pediments, particularly in areas where land use pressure is high. The technique is recommended for areas with a low gradient and rainfall of less than 600 mm.
The bunds capture and retain runoff for several days. Infiltration of the water into the soil increases, and there is a gradual build-up of sediment behind the bunds, creating favourable conditions for the establishment of vegetation. Contour bunds for crops increase the area of land that can be farmed and its productivity thanks to their capacity to retain runoff and the shelter provided by trees planted along the bottom bund, which protects the crops. An advantage from the perspective of watershed development is that contour bunds constructed on plateaux areas protect areas downstream against heavy runoff.
Before constructing the contour bunds, it is essential to clarify the ownership status of the land where the measures are to be implemented and who the users will be, with a view to avoiding disputes later on.
When constructing the contour bunds, it is important to mark out the contour lines correctly and ensure that the earth is firmly compacted.
With some upkeep, stone or stone-lined contour bunds last at least 20 years. Earthen bunds do not last as long. Good vegetation cover established along the bunds increases their lifetime.
The Sahel is a region where the population has always faced a high degree of climate variability, manifested both in terms of time (unexpected dry spells can occur during the rainy season) and in terms of space (rainfall can vary greatly from one area to another). The population is mainly composed of small farmers and livestock keepers.
Over the last two decades, the effects of climate change have exacerbated the already difficult conditions. Accord¬ing to projections made by climatologists, the Sahel will experience a rise in temperatures combined with highly variable rainfall and an increase in extreme weather events.
The Soil and Water conservation and rehabilitation techniques have helped people in the Sahel to manage their ecosystems more effectively and improve their productive land. As a result, communities are better prepared to cope with environmental changes (changes in the climate, land degradation, etc.) and the im¬pact of shocks, particularly droughts.
2.3 Photos of the Technology
2.5 Country/ region/ locations where the Technology has been applied and which are covered by this assessment
Region/ State/ Province:
Further specification of location:
Regions of Tillabéri, Filingué, Ouallam, Téra and Tahoua
Specify the spread of the Technology:
- evenly spread over an area
If precise area is not known, indicate approximate area covered:
- 10-100 km2
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.):
Developed, implemented and disseminated as part of projects and programmes undertaken from the 1980s onwards to combat desertification and improve natural resource management. Implemented by GIZ (German Federal Enterprise for International Cooperation), 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)
3. Classification of the SLM Technology
3.1 Main purpose(s) of the Technology
- reduce, prevent, restore land degradation
- adapt to climate change/ extremes and its impacts
3.2 Current land use type(s) where the Technology is applied
- Annual cropping
- Tree and shrub cropping
Annual cropping - Specify crops:
- oilseed crops - groundnuts
- cereals - millet
- cereals - sorghum
- legumes and pulses - peas
Tree and shrub cropping - Specify crops:
- mango, mangosteen, guava
Number of growing seasons per year:
Longest growing period in days: 120; Longest growing period from month to month: August to October
- (Semi-)natural forests/ woodlands
(Semi-)natural forests/ woodlands: Specify management type:
- Selective felling
Products and services:
- Fruits and nuts
- Other forest products
- Grazing/ browsing
major cash crop: Ground nut
major food crops: Millet
other: Sorghum, cow pea and mangoes
Major land use problems (compiler’s opinion): crusting, surface runoff, water and wind erosion, unadapted land use methods, rapidly growing population increasing pressure on land, reduced or abandoned fallow periods, insecure access to land
Type of cropping system and major crops comments: farmers are mainly agropastoralists with some communities specialised on pure pastoralism
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:
3.5 SLM group to which the Technology belongs
- cross-slope measure
3.6 SLM measures comprising the Technology
- V1: Tree and shrub cover
- S2: Bunds, banks
Type of vegetative measures: aligned: -contour
3.7 Main types of land degradation addressed by the Technology
soil erosion by water
- Wt: loss of topsoil/ surface erosion
chemical soil deterioration
- Cn: fertility decline and reduced organic matter content (not caused by erosion)
physical soil deterioration
- Pc: compaction
- Pk: slaking and crusting
- Bc: reduction of vegetation cover
- Ha: aridification
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), population pressure (rapidly growing population increasing pressure on land), land tenure (insecure access to land and collectively managed common 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
4. Technical specifications, implementation activities, inputs, and costs
4.1 Technical drawing of the Technology
Technical specifications (related to technical drawing):
Technical knowledge required for field staff / advisors: moderate
Technical knowledge required for land users: low
Main technical functions: control of dispersed runoff: retain / trap, control of dispersed runoff: impede / retard, control of concentrated runoff: retain / trap, control of concentrated runoff: impede / retard, improvement of ground cover, stabilisation of soil (eg by tree roots against land slides), increase in nutrient availability (supply, recycling,…), increase of infiltration, increase / maintain water stored in soil, water harvesting / increase water supply, sediment retention / trapping, sediment harvesting, promotion of vegetation species and varieties (quality, eg palatable fodder)
Secondary technical functions: improvement of surface structure (crusting, sealing), improvement of topsoil structure (compaction), increase in organic matter, reduction in wind speed
Vegetative material: T : trees / shrubs
Vegetation is used for stabilisation of structures.
MDR, Niger, Recueil des fiches
4.2 General information regarding the calculation of inputs and costs
Specify currency used for cost calculations:
4.3 Establishment activities
|1.||The contour bunds are built in staggered rows along the natural contour of the land with the open end facing uphill.|
|2.||Downslope of the structure, a water collection ditch 0.50 m wide and 0.30 m deep is dug.|
|3.||The earth excavated from the ditch is piled up and compacted to construct the main bund|
|4.||When used for growing crops, a third of the total surface area inside the contour bunds is loosened by subsoiling|
|5.||Trees are planted along the main bund to stabilise the structure|
4.5 Maintenance/ recurrent activities
|1.||Damages caused by excessive rainfall need to be repaired quickly|
4.7 Most important factors affecting the costs
Describe the most determinate factors affecting the costs:
Labour: 54 man-days per ha.
Equipment: pickaxes, shovels, wheelbarrows, water-tube level.
Other costs: hire of machine for subsoiling (1 day per ha).
5. Natural and human environment
- < 250 mm
- 251-500 mm
- 501-750 mm
- 751-1,000 mm
- 1,001-1,500 mm
- 1,501-2,000 mm
- 2,001-3,000 mm
- 3,001-4,000 mm
- > 4,000 mm
Thermal climate class: subtropics
Slopes on average:
- flat (0-2%)
- gentle (3-5%)
- moderate (6-10%)
- rolling (11-15%)
- hilly (16-30%)
- steep (31-60%)
- very steep (>60%)
- mountain slopes
- hill slopes
- valley floors
- 0-100 m a.s.l.
- 101-500 m a.s.l.
- 501-1,000 m a.s.l.
- 1,001-1,500 m a.s.l.
- 1,501-2,000 m a.s.l.
- 2,001-2,500 m a.s.l.
- 2,501-3,000 m a.s.l.
- 3,001-4,000 m a.s.l.
- > 4,000 m a.s.l.
Soil depth on average:
- very shallow (0-20 cm)
- shallow (21-50 cm)
- moderately deep (51-80 cm)
- deep (81-120 cm)
- very deep (> 120 cm)
Soil texture (topsoil):
- medium (loamy, silty)
- fine/ heavy (clay)
Topsoil organic matter:
- low (<1%)
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)
Soil fertility is very low - medium
Soil drainage / infiltration is poor - medium
Soil water storage capacity is low - medium
5.4 Water availability and quality
Ground water table:
Availability of surface water:
Water quality (untreated):
for agricultural use only (irrigation)
5.6 Characteristics of land users applying the Technology
Sedentary or nomadic:
Market orientation of production system:
- subsistence (self-supply)
- mixed (subsistence/ commercial)
- 10-50% of all income
Relative level of wealth:
- very poor
Level of mechanization:
- manual work
- animal traction
Indicate other relevant characteristics of the land users:
Population density: 10-50 persons/km2
Annual population growth: 3% - 4%
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), but surplus is sold on market (medium agropastoralists). Commercial markets: some vegetable growing and pastoralists.
Level of mechanization: Ox and donkey for animal traction
5.7 Average area of land used by land users applying the Technology
- < 0.5 ha
- 0.5-1 ha
- 1-2 ha
- 2-5 ha
- 5-15 ha
- 15-50 ha
- 50-100 ha
- 100-500 ha
- 500-1,000 ha
- 1,000-10,000 ha
- > 10,000 ha
Is this considered small-, medium- or large-scale (referring to local context)?
5.8 Land ownership, land use rights, and water use rights
- communal/ village
Land use rights:
- open access (unorganized)
Water use rights:
- open access (unorganized)
5.9 Access to services and infrastructure
employment (e.g. off-farm):
roads and transport:
drinking water and sanitation:
6. Impacts and concluding statements
6.1 On-site impacts the Technology has shown
risk of production failure
Water availability and quality
demand for irrigation water
Income and costs
food security/ self-sufficiency
SLM/ land degradation knowledge
livelihood and human well-being
Contour bunds for crops increase the area of land that can be farmed and its productivity thanks to their capacity to retain runoff and the shelter provided by trees planted along the bottom bund, which protects the crops
Water cycle/ runoff
harvesting/ collection of water
groundwater table/ aquifer
soil crusting/ sealing
nutrient cycling/ recharge
soil organic matter/ below ground C
Biodiversity: vegetation, animals
biomass/ above ground C
Climate and disaster risk reduction
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?|
Climate-related extremes (disasters)
|How does the Technology cope with it?|
|local rainstorm||not well|
|How does the Technology cope with it?|
|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|
Physical structures can be biologically stabilized through planting of grass, bushes or trees. Damages are generally small but need to be repaired quickly.
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?
The techniques were implemented with food for work in the 1990s to 2000. At the end, the work provided by land users was not compensated. Only small equipment and transportation were provided for free.
50% of land user families have adopted the Technology without any external material support
There is a little trend towards spontaneous adoption of the Technology
Some adoption (without support by the project) has been observed in some places. The level of replication is however limited to locations where stones are available nearby. Otherwise transportation becomes a problem. Potential for replication depends on the type of terrain, there being a nearby supply of the materials needed (stone). Subsoiling needs mechanical treatment by tractor.
6.7 Strengths/ advantages/ opportunities of the Technology
|Strengths/ advantages/ opportunities in the land user’s view|
|Contour bunds for crops increase the area of land that can be farmed and its productivity thanks to their capacity to retain runoff and the shelter provided by trees planted along the bottom bund, which protects the crops.|
|Strengths/ advantages/ opportunities in the compiler’s or other key resource person’s view|
|In a low-rainfall scenario, the construction of contour bunds helps to restore vegetation cover on vast areas of denuded land from the first year after they are established. Infiltration of the water into the soil increases, and there is a gradual build-up of sediment behind the bunds, creating favourable conditions for the establishment of vegetation.|
|Good vegetation cover established along the bunds con- tributes to lowering soil temperature and providing pro- tection from wind erosion along the entire length of the patch.|
|The construction of contour bunds upstream of river basins reduces the risk of gully erosion and siltation downstream.|
|In Niger, it is mainly women who have benefitted from efforts to rehabilitate land on the plateaux. With the support of development projects, women were able to secure five-year leases from land owners.|
|This technique transforms unproductive land into land that is economically valuable.|
6.8 Weaknesses/ disadvantages/ risks of the Technology and ways of overcoming them
|Weaknesses/ disadvantages/ risks in the land user’s view||How can they be overcome?|
|There are also disadvantages associated with subsoiling in the contour bunds. Although subsoiling permits rapid, relatively deep infiltration, the water is situated below the level where the roots of young crops or grasses are growing, which means that the infiltrated water is not used optimally in the initial stages. Furthermore, the surface of the subsoiled land becomes hard again after several years of cultivation, because the soil structure is broken down owing to a concentration of fine particles of earth in the grooves of the subsoil, which can clog up the pores of the soil.|
|Weaknesses/ disadvantages/ risks in the compiler’s or other key resource person’s view||How can they be overcome?|
|Patches with impermeable bunds are not appropriate when there are heavy rains, as the flow of water can destroy the bunds.||The extensive work required to construct the contour bunds means that the community must be strongly motivated and well organised.|
|Contour bunds for growing crops can be used to restore land that has become unproductive. This technique is not, however, very cost-effective, because of the scale of the work involved.||When constructing the contour bunds, it is important to mark out the contour lines correctly and ensure that the earth is firmly compacted.|
|The distribution of water in the contour bunds is often uneven, because the terrain is not level, which means that production varies considerably from one area to another|
|When there is heavy rain, runoff accumulates at the lowest point of the collection ditch, which can sometimes cause rilling|
|There is a risk of the patches becoming waterlogged, which can damage the crops|
7. References and links
7.1 Methods/ sources of information
- field visits, field surveys
- interviews with land users
When were the data compiled (in the field)?
7.2 References to available publications
Title, author, year, ISBN:
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.
Available from where? Costs?
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