Technologies

Contour bunds for crops and forest/rangeland [Niger]

Banquettes agricoles et sylvo-pastorales (French)

technologies_1652 - Niger

Completeness: 78%

1. معلومات عامة

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

Key resource person(s)

SLM specialist:
SLM specialist:

Mamadou Abdou Gaoh Sani

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

Niger

SLM specialist:

Dorlöchter-Sulser Sabine

Misereor

Germany

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:

نعم

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?

لا

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

Description:

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

بلد:

Niger

Region/ State/ Province:

Niger

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

الأراضي الزراعية

الأراضي الزراعية

  • 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:
  • 1
حددها:

Longest growing period in days: 120; Longest growing period from month to month: August to October

Forest/ woodlands

Forest/ woodlands

  • (Semi-)natural forests/ woodlands
(Semi-)natural forests/ woodlands: Specify management type:
  • Selective felling
Products and services:
  • Timber
  • Fuelwood
  • Fruits and nuts
  • Other forest products
  • Grazing/ browsing
Comments:

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:
  • rainfed

3.5 SLM group to which the Technology belongs

  • agroforestry
  • cross-slope measure

3.6 SLM measures comprising the Technology

vegetative measures

vegetative measures

  • V1: Tree and shrub cover
structural measures

structural measures

  • S2: Bunds, banks
Comments:

Type of vegetative measures: aligned: -contour

3.7 Main types of land degradation addressed by the Technology

soil erosion by water

soil erosion by water

  • Wt: loss of topsoil/ surface erosion
chemical soil deterioration

chemical soil deterioration

  • Cn: fertility decline and reduced organic matter content (not caused by erosion)
physical soil deterioration

physical soil deterioration

  • Pc: compaction
  • Pk: slaking and crusting
biological degradation

biological degradation

  • Bc: reduction of vegetation cover
water degradation

water degradation

  • Ha: aridification
Comments:

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

Aligned: -contour
Vegetative material: T : trees / shrubs
Vegetation is used for stabilisation of structures.

Author:

MDR, Niger, Recueil des fiches

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. 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

Activity Timing/ frequency
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

5.1 Climate

Annual rainfall
  • < 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
Agro-climatic zone
  • semi-arid

Thermal climate class: subtropics

5.2 Topography

Slopes on average:
  • flat (0-2%)
  • gentle (3-5%)
  • moderate (6-10%)
  • rolling (11-15%)
  • hilly (16-30%)
  • steep (31-60%)
  • very steep (>60%)
Landforms:
  • plateau/plains
  • ridges
  • mountain slopes
  • hill slopes
  • footslopes
  • valley floors
Altitudinal zone:
  • 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.

5.3 Soils

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:

5-50 m

Availability of surface water:

medium

Water quality (untreated):

for agricultural use only (irrigation)

5.5 Biodiversity

Species diversity:
  • low

5.6 Characteristics of land users applying the Technology

Sedentary or nomadic:
  • Semi-nomadic
Market orientation of production system:
  • subsistence (self-supply)
  • mixed (subsistence/ commercial)
Off-farm income:
  • 10-50% of all income
Relative level of wealth:
  • very poor
  • poor
Level of mechanization:
  • manual work
  • animal traction
Gender:
  • men
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)?
  • small-scale

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

Land ownership:
  • state
  • communal/ village
Land use rights:
  • open access (unorganized)
Water use rights:
  • open access (unorganized)

5.9 Access to services and infrastructure

health:
  • poor
  • moderate
  • good
education:
  • poor
  • moderate
  • good
technical assistance:
  • poor
  • moderate
  • good
employment (e.g. off-farm):
  • poor
  • moderate
  • good
markets:
  • poor
  • moderate
  • good
energy:
  • poor
  • moderate
  • good
roads and transport:
  • poor
  • moderate
  • good
drinking water and sanitation:
  • poor
  • moderate
  • good
financial services:
  • poor
  • moderate
  • good

6. Impacts and concluding statements

6.1 On-site impacts the Technology has shown

Socio-economic impacts

Production

crop production

decreased
increased

fodder production

decreased
increased

animal production

decreased
increased

wood production

decreased
increased

risk of production failure

increased
decreased

production area

decreased
increased
Water availability and quality

demand for irrigation water

increased
decreased
Income and costs

farm income

decreased
increased

Socio-cultural impacts

food security/ self-sufficiency

reduced
improved

SLM/ land degradation knowledge

reduced
improved

livelihood and human well-being

decreased
increased
Comments/ specify:

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

Ecological impacts

Water cycle/ runoff

harvesting/ collection of water

reduced
improved

surface runoff

increased
decreased

groundwater table/ aquifer

lowered
recharge
Soil

soil moisture

decreased
increased

soil cover

reduced
improved

soil loss

increased
decreased

soil crusting/ sealing

increased
reduced

soil compaction

increased
reduced

nutrient cycling/ recharge

decreased
increased

soil organic matter/ below ground C

decreased
increased
Biodiversity: vegetation, animals

biomass/ above ground C

decreased
increased

plant diversity

decreased
increased
Climate and disaster risk reduction

wind velocity

increased
decreased

6.2 Off-site impacts the Technology has shown

downstream flooding

increased
reduced

downstream siltation

increased
decreased

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
Comments:

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)?
Short-term returns:

positive

Long-term returns:

positive

How do the benefits compare with the maintenance/ recurrent costs (from land users' perspective)?
Short-term returns:

positive

Long-term returns:

positive

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?
  • 11-50%
Comments:

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)?

01/07/2012

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?

http://agriwaterpedia.info/wiki/Main_Page

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