Technologies

Retention ditches for soil and water conservation [Kenya]

Mitaro ya kuhifadhi maji (Kiswahili)

technologies_6675 - Kenya

Completeness: 94%

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)

land user:

Odongo Rosemary Ogola

Welthungerhilfe

Kenya

SLM specialist:
SLM specialist:
SLM specialist:
Name of project which facilitated the documentation/ evaluation of the Technology (if relevant)
Soil protection and rehabilitation for food security (ProSo(i)l)
Name of the institution(s) which facilitated the documentation/ evaluation of the Technology (if relevant)
Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ)
Name of the institution(s) which facilitated the documentation/ evaluation of the Technology (if relevant)
Alliance Bioversity and International Center for Tropical Agriculture (Alliance Bioversity-CIAT) - Kenya

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:

Ja

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?

Nee

Comments:

Farmers who have implemented the technology have been able to control surface runoff at their farms.

1.5 Reference to Questionnaire(s) on SLM Approaches (documented using WOCAT)

Community Resource Persons (CRP) in agricultural extension
approaches

Community Resource Persons (CRP) in agricultural extension [Kenya]

Community Resource Persons (CRP) form a farmer-to-farmer learning approach that bridges the gap in agricultural extension, increases farmers' access to agricultural information (SLM knowledge), and increases the adoption of SLM practices.

  • Compiler: William Akwanyi

2. Description of the SLM Technology

2.1 Short description of the Technology

Definition of the Technology:

Retention ditches are channels aligned along the contour which are designed for surface runoff management. They improve water infiltration into the ground and prevent soil erosion.

2.2 Detailed description of the Technology

Description:

Retention ditches are soil and water conservation practices. They are channels dug along contours (i.e., across the slope), especially at the uppermost part of the farm to retain stormwater/ surface runoff. They typically comprise two components: (a) vegetational-biological and (b) mechanical-structural components which are integrated to collect surface runoff, allowing for sediment carried by runoff to settle as water infiltrates into the ground. The mechanical-structural component consists of channels dug in such a way that they follow the contour and run perpendicular to the flow of water in areas where runoff naturally flows or collects. The soil excavated from the ditch forms a bund below the ditch. Retention ditches prevent surface runoff from outside the farm from flowing into or through the farm. The vegetational-biological component consists of plants grown on the bunds. The plant roots bind the soil thus increasing the slope stability, especially of the bunds; thus, preventing soil from collapsing and falling back into the channel. Retention ditches thus harvest and retain water (especially in low rainfall areas) preventing fertile soil from being washed away by surface runoff and increasing water availability for plants. In high-rainfall areas, they play the role of discharging excessive runoff into waterways.

Retention ditches are dug to about 60 cm deep and about 50 cm wide. To ensure stability, especially in areas with unstable soils, the top width is made wider than the bottom width allowing for slanting walls that are more stable than vertical walls. An understanding of the slope angle is an important factor in the designing and construction of retention ditches. A line-level (a spirit level attached to a string suspended between two poles) can be used to determine the measure slope. The slope angle determines the size of the ditch (depth and width) and the spacing between successive ditches on the same piece of land. In low-rainfall areas (such as Siaya), retention ditches are spaced at about 50 – 70 m while in high-rainfall areas the space between the ditches are closer (about 20 m). Similarly, the size of the retention ditches increases with increasing slope.

Some crops, especially bananas, arrowroot, etc. that demand a lot of water can be established in the ditches. Maintenance of retention ditches involves regular desilting, whenever the ditch is about 1/3 filled with silt. Hoes, shovels/ spades, and a panga (machete) are some of the tools used in digging and maintaining retention ditches. Farmers like retention ditches because they help in controlling soil erosion.

2.3 Photos of the Technology

General remarks regarding photos:

Photos taken during the dry season.

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

Country:

Kenya

Region/ State/ Province:

Siaya County, Nyanza Region

Further specification of location:

Uloma Village, Bondo Municipality, Bondo Sub-county

Specify the spread of the Technology:
  • evenly spread over an area
If precise area is not known, indicate approximate area covered:
  • < 0.1 km2 (10 ha)
Is/are the technology site(s) located in a permanently protected area?

Nee

Comments:

The farm where the technology is implemented is not in a protected area.

2.6 Date of implementation

Indicate year of implementation:

2018

2.7 Introduction of the Technology

Specify how the Technology was introduced:
  • through projects/ external interventions
Comments (type of project, etc.):

Soil Protection and Rehabilitation of Degraded Soil for Food Security (ProSoil) project

3. Classification of the SLM Technology

3.1 Main purpose(s) of the Technology

  • improve production
  • reduce, prevent, restore land degradation
  • protect a watershed/ downstream areas – in combination with other Technologies
  • preserve/ improve biodiversity
  • adapt to climate change/ extremes and its impacts

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

Land use mixed within the same land unit:

Ja

Specify mixed land use (crops/ grazing/ trees):
  • Agro-silvopastoralism

Cropland

Cropland

  • Annual cropping
  • Perennial (non-woody) cropping
  • Tree and shrub cropping
Annual cropping - Specify crops:
  • fodder crops - other
  • fodder crops - grasses
  • cereals - maize
  • vegetables - other
  • legumes and pulses - other
  • legumes and pulses - beans
Annual cropping system:

Fallow - maize/sorghum/millet intercropped with legume

Perennial (non-woody) cropping - Specify crops:
  • banana/plantain/abaca
  • fodder crops - grasses
  • fodder crops - legumes, clover
Tree and shrub cropping - Specify crops:
  • fodder trees (Calliandra, Leucaena leucocephala, Prosopis, etc.)
  • avocado
  • fruits, other
  • mango, mangosteen, guava
  • papaya
Number of growing seasons per year:
  • 2
Specify:

Long and short rain seasons

Is intercropping practiced?

Ja

If yes, specify which crops are intercropped:

Maize and legumes e.g., beans

Is crop rotation practiced?

Ja

If yes, specify:

Some sections of the farm are left fallow during the short rains to allow for soil regeneration.

Grazing land

Grazing land

Intensive grazing/ fodder production:
  • Cut-and-carry/ zero grazing
  • Improved pastures
Animal type:
  • cattle - dairy and beef (e.g. zebu)
  • poultry
Is integrated crop-livestock management practiced?

Ja

If yes, specify:

Fodder (nappier grass) planted on the berms is fed to the cattle. The manure from the cattle and droppings from the chicken is used as manure for the crops.

Products and services:
  • milk
  • eggs
  • meat
Species:

cattle - dairy and beef (e.g. zebu)

Count:

3

Species:

poultry

Count:

100

Comments:

There are assorted trees on the farm, including fruit trees. Some of the trees are planted on the berm of the retention ditches.

3.3 Has land use changed due to the implementation of the Technology?

Has land use changed due to the implementation of the Technology?
  • No (Continue with question 3.4)

3.4 Water supply

Water supply for the land on which the Technology is applied:
  • rainfed
Comments:

Crops are planted only during the rainy seasons since there is no irrigation.

3.5 SLM group to which the Technology belongs

  • cross-slope measure
  • water diversion and drainage

3.6 SLM measures comprising the Technology

vegetative measures

vegetative measures

  • V1: Tree and shrub cover
  • V2: Grasses and perennial herbaceous plants
structural measures

structural measures

  • S4: Level ditches, pits
Comments:

Trees and grasses are planted on the berms of the retention ditches.

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
  • Wg: gully erosion/ gullying
Comments:

The retention ditches, especially when applied at the top of a plot and the design is to heap the soil below the channel ('fanya chini') has helped control gully erosion. Gullies were common in the farm before the digging of the retention ditches.

3.8 Prevention, reduction, or restoration of land degradation

Specify the goal of the Technology with regard to land degradation:
  • reduce land degradation
  • restore/ rehabilitate severely degraded land
Comments:

The retention ditches saved the land from gullies, and are still controlling soil erosion.

4. Technical specifications, implementation activities, inputs, and costs

4.1 Technical drawing of the Technology

Technical specifications (related to technical drawing):

Ditch dimensions: length = 70m, width = 50cm, depth = 60cm
Slope of the field = 4%
Plants on the berm: nappier grass

Author:

William Akwanyi

Date:

01/07/2023

4.2 General information regarding the calculation of inputs and costs

Specify how costs and inputs were calculated:
  • per Technology area
Indicate size and area unit:

0.4 ha

other/ national currency (specify):

KES

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

122.95

Indicate average wage cost of hired labour per day:

300

4.3 Establishment activities

Activity Timing (season)
1. Slope measurement and determination of position for the retention ditch During the dry season
2. Digging the ditches Before onset of rains
Comments:

The ditches should be constructed during the dry season or before the rains start when the soil is light and easy to remove from the ditches.

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 Digging the ditches Man days 10.0 300.0 3000.0 100.0
Equipment Hoe No. 1.0 80.0 80.0 100.0
Equipment Panga (broad blade) No. 1.0 60.0 60.0 100.0
Equipment Wheelbarrow No. 1.0 800.0 800.0 100.0
Equipment Spade No. 1.0 90.0 90.0 100.0
Equipment Planting rope No. 1.0 60.0 60.0 100.0
Equipment Spirit level No. 1.0 600.0 600.0
Other Slope measurement and determination of position for the retention ditch (professional service) Professional service 1.0 2000.0 2000.0
Total costs for establishment of the Technology 6690.0
Total costs for establishment of the Technology in USD 54.41
If land user bore less than 100% of costs, indicate who covered the remaining costs:

ProSoil project

Comments:

The costs of the implements are KES 400/- for a hoe, KES 4,000/- for a wheelbarrow, KES 300/- for a planting rope and broad blade, KES 3,000/- for a spirit level, and KES 450/- for a spade. It is assumed that the farmer will be able to use the hoe, planting rope, broad blade, and spade over a period of 5 years, and a wheelbarrow over a period of 10 years before these implements will have depreciated to a point where they will not be useable. The cost is thus spread over the years when the farmer will be able to use the implement.

4.5 Maintenance/ recurrent activities

Activity Timing/ frequency
1. Desilting Whenever the ditch is about 1/3 filled with silt
Comments:

Maintenance activities do not happen at regular intervals but depend on volume of runoff and amount of silt carried by surface runoff for desilting the ditch, rate of growth of weeds for weeding, and factors that lead to lead of plants for plant re-establishment.

4.6 Costs and inputs needed for maintenance/ recurrent activities (per year)

If you are unable to break down the costs in the table above, give an estimation of the total costs of maintaining the Technology:

2000.0

Comments:

the above cost is based on the farmer's estimate.

4.7 Most important factors affecting the costs

Describe the most determinate factors affecting the costs:

Rate of man-days vary from one place to another and also depend on the kind of work.

Exchange rate for January 2023, source: European Commission/ InfoEuro online at https://commission.europa.eu/funding-tenders/procedures-guidelines-tenders/information-contractors-and-beneficiaries/exchange-rate-inforeuro_en

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
Specifications/ comments on rainfall:

Rainfall pattern is bimodal. Monthly rainfall variability is high with some months such as January recording less than 5 mm of total rainfall.

Indicate the name of the reference meteorological station considered:

Bondo Meteorological Station

Agro-climatic zone
  • semi-arid

The area is found near Lake Victoria which influences the climate.

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.
Indicate if the Technology is specifically applied in:
  • convex situations
Comments and further specifications on topography:

Retention ditches divert the flow of surface runoff. The slope of the farmer's field is 4%.

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)
Soil texture (> 20 cm below surface):
  • medium (loamy, silty)
Topsoil organic matter:
  • medium (1-3%)
If available, attach full soil description or specify the available information, e.g. soil type, soil PH/ acidity, Cation Exchange Capacity, nitrogen, salinity etc.

N/A

5.4 Water availability and quality

Ground water table:

5-50 m

Availability of surface water:

good

Water quality (untreated):

poor drinking water (treatment required)

Water quality refers to:

both ground and surface water

Is water salinity a problem?

Nee

Is flooding of the area occurring?

Nee

Comments and further specifications on water quality and quantity:

There are several boreholes in the area and according to interviews with some borehole owners, the depts are not more than 50 metres. Lake Victoria is a permanent surface water body in the area.

5.5 Biodiversity

Species diversity:
  • medium
Habitat diversity:
  • medium
Comments and further specifications on biodiversity:

The area has high agrobiodiversity as most farms are under crops and trees.

5.6 Characteristics of land users applying the Technology

Sedentary or nomadic:
  • Semi-nomadic
Market orientation of production system:
  • mixed (subsistence/ commercial)
Off-farm income:
  • 10-50% of all income
Relative level of wealth:
  • average
Individuals or groups:
  • individual/ household
Level of mechanization:
  • manual work
Gender:
  • women
  • men
Age of land users:
  • middle-aged
  • elderly
Indicate other relevant characteristics of the land users:

The farmer uses the land together with his other family members.

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)?
  • medium-scale
Comments:

Farmers with more than 2 ha in the area are considered to have large pieces of land since there is high level of land fragmentation in the area.

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

Land ownership:
  • individual, titled
Land use rights:
  • individual
Water use rights:
  • communal (organized)
Are land use rights based on a traditional legal system?

Nee

Specify:

Each landowner has full control of the way he/ she wants to use his/ her land.

Comments:

The farmer has a title for his piece of land.

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
Comments:

The above rating varies from one village to the other.

6. Impacts and concluding statements

6.1 On-site impacts the Technology has shown

Socio-economic impacts

Production

crop production

decreased
increased
Quantity before SLM:

2

Quantity after SLM:

4

Comments/ specify:

Quantity refers to the number of 90 Kg bags of maize produced per acre. Based on estimation by the farmer.

crop quality

decreased
increased
Comments/ specify:

Not easy to quantify but according to the farmer, the crops are doing better compared to how they were before the retention ditches were dug.

fodder production

decreased
increased
Quantity before SLM:

1

Quantity after SLM:

3

Comments/ specify:

Quantity refers to harvesting cycles for nappier grass from the same farm. Based on estimation by the farmer.

fodder quality

decreased
increased
Comments/ specify:

Not easy to quantify but according to the farmer, fodder is doing better compared to how it was before the retention ditches were dug.

animal production

decreased
increased
Quantity before SLM:

1

Quantity after SLM:

3

Comments/ specify:

Quantity refers to the amount of milk in litres from one cow. Milk production is often at the peak during early lactation months. Based on estimation by the farmer.

risk of production failure

increased
decreased
Quantity before SLM:

80

Quantity after SLM:

40

Comments/ specify:

Quantity refers to the percentage probability of the crop failing to do well. Based on estimation by the farmer.

Income and costs

workload

increased
decreased
Comments/ specify:

Refers to the number of hours that the farmer can be free in any working day. During the rainy season, the farmer spends some time desilting the ditches. Based on estimation by the farmer.

Socio-cultural impacts

food security/ self-sufficiency

reduced
improved
Quantity before SLM:

5

Quantity after SLM:

2

Comments/ specify:

Quantity refers to the number of months in a year when there is total lack of food in the house, and the farmer has to buy all the food required in the house. Based on estimation by the farmer.

SLM/ land degradation knowledge

reduced
improved
Quantity before SLM:

10%

Quantity after SLM:

80%

Comments/ specify:

Quantity refers to the estimated percentage of knowledge in SLM/ land management. This is a farmer's estimate.

Ecological impacts

Water cycle/ runoff

harvesting/ collection of water

reduced
improved
Comments/ specify:

Not easy to quantify. Based on estimation by the farmer.

surface runoff

increased
decreased
Comments/ specify:

Refers to the amount of water that flows through the farm. Not easy to quantify. Based on estimation by the farmer.

Soil

soil loss

increased
decreased
Comments/ specify:

Not easy to quantify.

Biodiversity: vegetation, animals

Vegetation cover

decreased
increased
Comments/ specify:

Refers to the farmer's estimated percentage vegetation cover at the farm. Based on estimation by the farmer.

Specify assessment of on-site impacts (measurements):

No recorded data is available for reference. All are estimates based on the farmer's explanation or as given by her.

6.2 Off-site impacts the Technology has shown

downstream flooding

increased
reduced
Comments/ specify:

Not easy to quantify. Retention ditches have reduced the amount of water that flows to the farms in the lower areas. This has reduced soil erosion in these farms.

downstream siltation

increased
decreased
Comments/ specify:

Not easy to quantify. All silt is deposited in the retention ditches and scooped by the farmer for replenishing parts of the farm with low soil levels.

damage on neighbours' fields

increased
reduced
Comments/ specify:

Not easy to quantify. Retention ditches have reduced the amount of water that flows to the farms in the lower areas. This has reduced soil erosion in these farms.

Specify assessment of off-site impacts (measurements):

It was not possible for the farmer to quantify the above.

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
seasonal temperature dry season increase moderately

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:

very positive

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

very positive

Long-term returns:

very positive

Comments:

The retention ditches have generally improved crop production.

6.5 Adoption of the Technology

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

6.6 Adaptation

Has the Technology been modified recently to adapt to changing conditions?

Nee

6.7 Strengths/ advantages/ opportunities of the Technology

Strengths/ advantages/ opportunities in the land user’s view
Controls soil erosion. Silt collected in the ditches is used to replenish other sections of the farm with poor soils.
Improved crop yields.
Strengths/ advantages/ opportunities in the compiler’s or other key resource person’s view
Controls road damage due to runoff as most of the water is collected by the ditches before it destroys the road.

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?
Establishment investment is capital and labour intensive. The farmer has to be committed.
Maintenance is labour intensive. The farmer has to be committed. Proper planning of farm work.
Weaknesses/ disadvantages/ risks in the compiler’s or other key resource person’s view How can they be overcome?
If not managed properly by regular removal of silt, the ditch can easily fill up. The farmer must be committed to remove silt regularly.
May overflow and collapse during high rainfall leading to high levels of soil erosion. Proper designing in consideration of runoff volumes and slope angle. Regular maintenance.

7. References and links

7.1 Methods/ sources of information

  • field visits, field surveys

One visit at one farm

  • interviews with land users

One farmer interviewed at his farm. Follow-up questions on phone.

  • interviews with SLM specialists/ experts

ProSoil team and project implementers from Welthungerhilfe consulted.

  • compilation from reports and other existing documentation

Siaya County Integrated Development Plan, 2018-2022 and online sources reviewed.

When were the data compiled (in the field)?

27/01/2023

Comments:

One field visit and several follow-up consultations.

7.2 References to available publications

Title, author, year, ISBN:

Climate Smart Extension Manual by KCEP - CRAL, 2021

Available from where? Costs?

Download free at https://www.kalro.org/files/kcep/CSA-extension-manual-18-06-21.pdf

7.3 Links to relevant online information

Title/ description:

Siaya County Integrated Development Plan, 2018-2022

URL:

https://repository.kippra.or.ke/bitstream/handle/123456789/1218/2018-2022%20%20Siaya%20County%20CIDP.pdf?sequence=1&isAllowed=y

7.4 General comments

1. Provide a function to be able to link the documented SLM to similar work that has been documented in other databases e.g., LandPortal, UNCCD, etc.
2. Some of the impacts (section 6) cannot be quantified.

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