Technologies

Semi-circular bunds (for crops and forest/rangeland) [Niger]

Demi-lunes (French)

technologies_1614 - Niger

Completeness: 82%

1. Informação geral

1.2 Detalhes do contato das pessoas capacitadas e instituições envolvidas na avaliação e documentação da tecnologia.

Pessoa(s)-chave

SLM specialist:
SLM specialist:

Sani Mamadou Abdou

Programme d’Appui à l’agriculture Productive (PROMAP), Niamey, Niger

Niger

Name of project which facilitated the documentation/ evaluation of the Technology (if relevant)
Good Practices in Soil and Water Conservation - A contribution to adaptation and farmers ́ resilience towards climate change 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

1.3 Condições em relação ao uso da informação documentada através de WOCAT

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

Sim

1.4 Declaração de sustentabilidade da tecnologia descrita

A tecnologia descrita aqui é problemática em relação a degradação da terra de forma que não pode ser declarada uma tecnologia sustentável de gestão de terra?

Não

2. Descrição da tecnologia de gestão sustentável da terra

2.1 Descrição curta da tecnologia

Definição da tecnologia:

Semi-circular bunds are used to rehabilitate degraded, denuded and hardened land for crop growing, grazing or forestry.

2.2 Descrição detalhada da tecnologia

Descrição:

This technique involves building low embankments with compacted earth or stones in the form of a semi-circle with the opening perpendicular to the flow of water and arranged in staggered rows. They are constructed on gently to moderately sloping pediments and plateau areas in order to rehabilitate areas that are degraded, denuded and/or affected by soil crusting.

Depending on their purpose, the areas inside the semi-circular bunds, enriched with organic fertiliser, are used for growing cereals (crop crescents) and for planting trees, bushes and/or grasses (forestry and pastoral crescents). Semi-circular bunds slow down and capture runoff, providing the plants inside them with the water they need. They therefore reduce the loss of water and the fertile layers of the soil. This is particularly advantageous when rain is scarce, as the semi-circular bunds channel water towards the plants, increasing the moisture available to them. In the medium term, rich sediment builds up behind the semi-circular bunds, which helps to protect and restore the land. The bunds ensure that the manure placed around the plants inside them is not washed away by heavy rains, and the ridge of the bund protects young plants from the wind and wind erosion. When they are used for reforestation, they increase the rate of survival of the trees planted in them. Cropland bunds enable crops to survive dry spells. Earthen bunds are not, however, suitable in a scenario with heavy rainfall. They do not allow water to filter through, which can result in the soil inside them becoming waterlogged and the plants being flooded. This can lower yields in the case of crops that do not tolerate excess water. In such conditions, stone bunds are preferable.

To establish semi-circular bunds on cropland, the following activities are required: marking out the contour line, laying out the lines of the semi-circular bunds in staggered rows, digging the microcatchment, forming the ridge downhill of the microcatchment, applying organic fertiliser (around 1 t per ha per year).
To establish semi-circular bunds on forestland the same steps are required, however instead of applying fertilizer, other steps include digging the holes, planting the trees, and sowing grass on the ridges. The earthen ridges around cropland bunds need to be rebuilt each year. It is recommended that the ridges of forest/rangeland bunds be maintained each year and raised if overflowing has occurred. Forest/rangeland sites should be protected from grazing animals in the first two to three years, until the vegetation is well established. This requires good community organisation. After dry years, forest/rangeland semi-circular bunds may have to be re-sown with grasses and replanted with trees.

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 Fotos da tecnologia

2.5 País/região/locais onde a tecnologia foi aplicada e que estão cobertos nesta avaliação

Country:

Niger

Region/ State/ Province:

Niger, Burkina Faso, Chad

Further specification of location:

Regions of Tillabéri, Filingué, Ouallam, Téra and Tahuoa in Niger; Bam region in Burkina Faso

Especifique a difusão da tecnologia :
  • Uniformemente difundida numa área
If precise area is not known, indicate approximate area covered:
  • 10-100 km2
Comentários:

Also implemented in Burkina Faso and Chad
Regions of Tillabéri, Filingué, Ouallam, Téra and Tahuoa in Niger; Bam region in Burkina Faso

2.6 Data da implementação

Caso o ano exato seja desconhecido, indique a data aproximada:
  • 10-50 years ago

2.7 Introdução da tecnologia

Especifique como a tecnologia foi introduzida:
  • através de projetos/intervenções externas
Comentários (tipos de projeto, 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. Classificação da tecnologia de gestão sustentável da terra

3.1 Principal/principais finalidade(s) da tecnologia

  • Reduz, previne, recupera a degradação do solo

3.2 Tipo(s) atualizado(s) de uso da terra onde a tecnologia foi aplicada

Terra de cultivo

Terra de cultivo

  • Cultura anual
Número de estações de cultivo por ano:
  • 1
Especifique:

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

Floresta/bosques

Floresta/bosques

  • Florestas/bosques (semi)naturais
(Semi-)natural forests/ woodlands: Specify management type:
  • Derrubada seletiva
Produtos e serviços:
  • Madeira
  • Lenha
  • Frutas e nozes
  • Outros produtos florestais
  • Pastagem/Alimentação de folhas e brotos
Comentários:

Major land use problems (compiler’s opinion): droughts, soil erosion, lack of water, surface runoff, soil crusting, unadapted land use methods, rapidly growing population increasing pressure on land, reduced or abandoned fallow periods, soil erosion, insecure access to land.

Cut-and-carry/ zero grazing, Improved pasture, agropastolralism

Livestock density: 1-10 LU /km2

3.4 Water supply

Abastecimento de água para a terra na qual a tecnologia é aplicada:
  • Misto de precipitação natural-irrigado

3.5 Grupo de gestão sustentável da terra ao qual pertence a tecnologia

  • Agrofloresta
  • Gestão de pastoralismo e pastagem

3.6 Medidas de gestão sustentável da terra contendo a tecnologia

Medidas estruturais

Medidas estruturais

  • S2: Barragens, bancos

3.7 Principais tipos de degradação da terra abordados pela tecnologia

Erosão do solo pela água

Erosão do solo pela água

  • Wt: Perda do solo superficial/erosão de superfície
Deteriorização química do solo

Deteriorização química do solo

  • Cn: declínio de fertilidade e teor reduzido de matéria orgânica (não causado pela erosão)
Deteriorização física do solo

Deteriorização física do solo

  • Pk: quebra e ressecamento
Degradação da água

Degradação da água

  • Ha: aridificação
Comentários:

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 community 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 Redução, prevenção ou recuperação da degradação do solo

Especifique o objetivo da tecnologia em relação a degradação da terra:
  • Reduzir a degradação do solo
  • Recuperar/reabilitar solo severamente degradado

4. Especificações técnicas, implementação de atividades, entradas e custos

4.1 Desenho técnico da tecnologia

Especificações técnicas (relacionada ao desenho técnico):

Source: Ministère du Développement Agricole Niger (without date): Recueil des fiches techniques en gestion des ressources naturelles et de productions agro-sylvo-pastorales.

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, increase of infiltration, increase / maintain water stored in soil, water harvesting / increase water supply, sediment retention / trapping, sediment harvesting
Secondary technical functions: improvement of surface structure (crusting, sealing), stabilisation of soil (eg by tree roots against land slides), increase in nutrient availability (supply, recycling,…), reduction in wind speed

Bund/ bank: semi-circular/V shaped trapezoidal
Depth of ditches/pits/dams (m): 0,15-0,20
Width of ditches/pits/dams (m): 2
Length of ditches/pits/dams (m): 4

4.2 Informação geral em relação ao cálculo de entradas e custos

Outro/moeda nacional (especifique):

CFA Franc

If relevant, indicate exchange rate from USD to local currency (e.g. 1 USD = 79.9 Brazilian Real): 1 USD =:

521,18

4.3 Atividades de implantação

Atividade Timing (season)
1. marking out the contour line
2. laying out the lines of the semi-circular bunds in stag- gered rows
3. digging the microcatchment
4. forming the ridge downhill of the microcatchment
5. applying organic fertiliser (around 1 t per ha per year) (only on cropland, this step is not required on forestland)
6. digging the holes (only on forestland)
7. planting the trees (only on forestland)
8. sowing grass on the ridges (only on forestland)

4.4 Custos e entradas necessárias para a implantação

Especifique a entrada Unidade Quantidade Custos por unidade Custos totais por entrada % dos custos arcados pelos usuários da terra
Mão-de-obra labour ha 1,0 201,5 201,5 100,0
Equipamento tools ha 1,0 17,3 17,3 100,0
Custos totais para a implantação da tecnologia 218,8
Total costs for establishment of the Technology in USD 0,42

4.5 Atividades recorrentes/manutenção

Atividade Calendarização/frequência
1. The earthen ridges around cropland bunds need to be rebuilt each year each year
2. the ridges of forest/rangeland bunds be maintained each year and raised if overflowing has occurred. each year
3. After dry years, forest/rangeland semi-circular bunds may have to be re-sown with grasses and replanted with trees. after dry years
4. Forest/rangeland sites should be protected from grazing animals in the first two to three years, until the vegetation is well established. in the first two to three years

4.6 Custos e entradas necessárias pata a manutenção/atividades recorrentes (por ano)

Comentários:

other costs for cropland semi-circular bunds: 10 cartloads of manure.
other costs for forestland semi-circular bunds:
• 625 tree seedlings
• 15 kg of grass seed
• cost of transporting 625 tree seedlings (2 cartloads)
• 120 seedlings to replace trees that die.

4.7 Fatores mais importantes que afetam os custos

Descreva os fatores mais determinantes que afetam os custos:

In the case of forest/rangeland semi-circular bunds, the availability of tree and grass seeds and seedlings is a vital factor. In the PDRT and PASP projects in Niger, the villages had nurseries, and members of the village land manage- ment committees collected grass seeds from rangelands to sow in the semi-circular bunds.

5. Ambiente naturale e humano

5.1 Clima

Precipitação pluviométrica anual
  • <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
Zona agroclimática
  • Semiárido

Thermal climate class: subtropics

5.2 Topografia

Encostas em média:
  • Plano (0-2%)
  • Suave ondulado (3-5%)
  • Ondulado (6-10%)
  • Moderadamente ondulado (11-15%)
  • Forte ondulado (16-30%)
  • Montanhoso (31-60%)
  • Escarpado (>60%)
Formas de relevo:
  • Planalto/planície
  • Cumes
  • Encosta de serra
  • Encosta de morro
  • Sopés
  • Fundos de vale
Zona de altitude:
  • 0-100 m acima do nível do mar
  • 101-500 m acima do nível do mar
  • 501-1.000 m acima do nível do mar
  • 1.001-1.500 m acima do nível do mar
  • 1.501-2.000 m acima do nível do mar
  • 2.001-2.500 m acima do nível do mar
  • 2.501-3.000 m acima do nível do mar
  • 3.001-4.000 m acima do nível do mar
  • > 4.000 m acima do nível do mar

5.3 Solos

Profundidade do solo em média:
  • Muito raso (0-20 cm)
  • Raso (21-50 cm)
  • Moderadamente profundo (51-80 cm)
  • Profundo (81-120 cm)
  • Muito profundo (>120 cm)
Textura do solo (solo superficial):
  • Médio (limoso, siltoso)
  • Fino/pesado (argila)
Matéria orgânica do solo superficial:
  • Médio (1-3%)

5.4 Disponibilidade e qualidade de água

Lençol freático:

5-50 m

Disponibilidade de água de superfície:

Médio

Qualidade da água (não tratada):

apenas para uso agrícola (irrigação)

5.5 Biodiversidade

Diversidade de espécies:
  • low

5.6 Características dos usuários da terra que utilizam a tecnologia

Orientação de mercado do sistema de produção:
  • Subsistência (autoabastecimento)
  • mixed (subsistence/ commercial)
Rendimento não agrícola:
  • 10-50% de toda renda
Nível relativo de riqueza:
  • Muito pobre
  • Pobre
Nível de mecanização:
  • Trabalho manual
  • Tração animal
Gênero:
  • Homens
Indique outras características relevantes dos usuários da terra:

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 seaonally carry out paid farm labour

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
É considerado pequena, média ou grande escala (referente ao contexto local)?
  • Pequena escala

5.8 Propriedade de terra, direitos de uso da terra e de uso da água

Propriedade da terra:
  • Estado
  • Comunitário/rural
Direitos do uso da terra:
  • Acesso livre (não organizado)
  • Comunitário (organizado)
Direitos do uso da água:
  • Acesso livre (não organizado)
  • Comunitário (organizado)
Comentários:

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

5.9 Acesso a serviços e infraestrutura

Saúde:
  • Pobre
  • Moderado
  • Bom
Educação:
  • Pobre
  • Moderado
  • Bom
Assistência técnica:
  • Pobre
  • Moderado
  • Bom
Emprego (p. ex. não agrícola):
  • Pobre
  • Moderado
  • Bom
Mercados:
  • Pobre
  • Moderado
  • Bom
Energia:
  • Pobre
  • Moderado
  • Bom
Vias e transporte:
  • Pobre
  • Moderado
  • Bom
Água potável e saneamento:
  • Pobre
  • Moderado
  • Bom
Serviços finais:
  • Pobre
  • Moderado
  • Bom

6. Impactos e declarações finais

6.1 Impactos no local mostrados pela tecnologia

Impactos socioeconômicos

Produção

Produção agrícola

Diminuído
Elevado
Comentários/especificar:

Cropland bunds constructed on abandoned farmland increase millet yields by 180 kg and straw yields by 400 kg per hectare per year

Produção de forragens

Diminuído
Elevado

Produção animal

Diminuído
Elevado
Comentários/especificar:

Forest/rangeland sites should be protected from grazing animals in the first two to three years, until the vegetation is well established. This requires good community organisation.

Produção de madeira

Diminuído
Elevado
Comentários/especificar:

Sites improved with semi-circular bunds for reforestation produce one stere of wood per hectare per year after ten years. The value of this production can increase further from the fifth year onwards to around 850,000 CFA francs per hectare

Disponibilidade e qualidade de água

Demanda por água para irrigação

Elevado
Diminuído
Renda e custos

Carga de trabalho

Elevado
Diminuído

Impactos socioculturais

Segurança alimentar/auto-suficiência

Reduzido
Melhorado

Atenuação de conflitos

Agravado
Melhorado

contribution to human well-being

decreased
increased
Comentários/especificar:

notably increses production of food, fodder and forest products

Impactos ecológicos

Ciclo hídrico/escoamento

Colheita/recolhimento de água

Reduzido
Melhorado

Escoamento superficial

Elevado
Diminuído
Solo

Umidade do solo

Diminuído
Elevado

Perda de solo

Elevado
Diminuído

Ressecamento/selagem do solo

Elevado
Reduzido

Ciclo e recarga de nutrientes

Diminuído
Elevado
Biodiversidade: vegetação, animais

Diversidade vegetal

Diminuído
Elevado

Diversidade animal

Diminuído
Elevado
Clima e redução de riscos de desastre

Velocidade do vento

Elevado
Diminuído
Outros impactos ecológicos

survival of planted trees

decreased
increased

6.2 Impactos externos mostrados pela tecnologia

Disponibilidade de água

Diminuído
Elevado

Cheias de jusante

Elevado
Reduzido

Sedimentação a jusante

Elevado
Diminuído

Capacidade de tamponamento/filtragem

Reduzido
Melhorado

Danos em áreas vizinhas

Elevado
Reduzido

Danos na infraestrutura pública/privada

Elevado
Reduzido

6.3 Exposição e sensibilidade da tecnologia às mudanças climáticas graduais e extremos/desastres relacionados ao clima (conforme o ponto de vista dos usuários da terra)

Mudança climática gradual

Mudança climática gradual
Estação do ano increase or decrease Como a tecnologia lida com isso?
Temperatura anual increase bem

Extremos (desastres) relacionados ao clima

Desastres meteorológicos
Como a tecnologia lida com isso?
Temporal local não bem
Tempestade de vento local bem
Desastres climatológicos
Como a tecnologia lida com isso?
Seca bem
Desastres hidrológicos
Como a tecnologia lida com isso?
Inundação geral (rio) não bem

Outras consequências relacionadas ao clima

Outras consequências relacionadas ao clima
Como a tecnologia lida com isso?
Período de crescimento reduzido não conhecido
Comentários:

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 Análise do custo-benefício

Como os benefícios se comparam aos custos de implantação (do ponto de vista dos usuários da terra)?
Retornos a curto prazo:

positivo

Retornos a longo prazo:

muito positivo

Como os benefícios se comparam aos custos recorrentes/de manutenção(do ponto de vista dos usuários da terra)?
Retornos a curto prazo:

positivo

Retornos a longo prazo:

muito positivo

Comentários:

Forest/rangeland sites should be protected from grazing animals in the first two to three years, until the vegetation is well established. Semi-circular bunds on forest/rangeland can achieve a remarkable regreening of the environment and promote biodiversity. Cropland bunds constructed on abandoned farmland increase millet yields by 180 kg and straw yields by 400 kg per hectare per year. Sites improved with semi-circular bunds for reforestation produce one stere of wood per hectare per year after ten years. The value of this production can increase further from the fifth year onwards to around 850,000 CFA francs per hectare.

6.5 Adoção da tecnologia

  • > 50%
Of all those who have adopted the Technology, how many did so spontaneously, i.e. without receiving any material incentives/ payments?
  • 11-50%
Comentários:

60% of land user families have adopted the Technology with external material support
The techniques were implemented with food for work in the 1990s to 2000. Between 2000 and 2012 the work provided by land users was not compensated. Only small equipment and transportation were provided for free.
40% of land user families have adopted the Technology without any external material support. 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.
There is a little trend towards spontaneous adoption of the Technology. Semi-circular bunds are applied for example in Niger, Burkina Faso, and Chad.
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.

6.7 Pontos fortes/vantagens/oportunidades da tecnologia

Strengths/ advantages/ opportunities in the compiler’s or other key resource person’s view
Semi-circular bunds slow down runoff and enable the harvested water to be used to good effect. Soil moisture increases and the loss of fertile layers of the soil is reduced.
Cropland bunds enable crops to survive dry spells. On abandoned farmland millet yields may increase by 180 kg and straw yields by 400 kg per hectare per year.
Semi-circular bunds on forest/rangeland can achieve a remarkable regreening of the environment and promote biodiversity. When they are used for reforestation, they increase the rate of survival of the trees planted in them. Sites improved with semi-circular bunds produce one stere of wood per hectare per year after ten years. The value of this production can increase further from the fifth year onwards to around 850,000 CFA francs per hectare.
In the medium term, rich sediment builds up behind the semi-circular bunds, which helps to protect and restore the land.

6.8 Pontos fracos, desvantagens/riscos da tecnologia e formas de superá-los

Weaknesses/ disadvantages/ risks in the compiler’s or other key resource person’s view How can they be overcome?
In the event of heavy runoff, a considerable amount of water accumulates inside the semi-circular bunds, and the ridges must be strong enough to withstand its weight. If the water overflows, it can create gaps in the bunds or cut out channels around the sides of them. The land must be hoed each year.
At some sites, rainwater infiltration increases in the first year after the semi-circular bunds have been constructed, but if the land is not hoed, this effect declines considerably in successive years. In such conditions, stone bunds are preferable.
Earthen bunds are not suitable in a scenario with heavy rainfall. They do not allow water to filter through, which can result in the soil inside them becoming waterlogged and the plants being flooded. This can lower yields in the case of crops that do not tolerate excess water (e.g. millet).
Animal production may be reduced because forest/rangeland sites should be protected from grazing animals in the first two to three years, until the vegetation is well established.
Labour-intensive work

7. Referências e links

7.1 Métodos/fontes de informação

  • field visits, field surveys
  • interviews with land users
When were the data compiled (in the field)?

01/07/2012

7.2 Referências às publicações disponíveis

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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