Technologies

Vegetative cross-slope barriers [Kenya]

Creation: 03/19/2023 6:53 p.m.
Update: 04/23/2024 4:40 p.m.
Compiler: William Akwanyi
Editors: George Onyango, Innocent Faith, Noel Templer, Tabitha Nekesa, Ahmadou Gaye, Siagbé Golli
Reviewers: William Critchley, Rima Mekdaschi Studer, Sally Bunning

technologies_6705 - Kenya

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Completeness: 92%

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:

Osundwa Amirah Munyolo

Welthungerhilfe farmer

Kenya

SLM specialist:

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SLM specialist:

{'additional_translations': {}, 'value': 'Innocent Faith', 'user_id': '202482', 'unknown_user': False, 'template': 'raw'}

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

Soil protection and rehabilitation for food security (ProSo(i)l) {'additional_translations': {}, 'value': 876, 'label': 'Name of the institution(s) which facilitated the documentation/ evaluation of the Technology (if relevant)', 'text': 'Alliance Bioversity and International Center for Tropical Agriculture (Alliance Bioversity-CIAT) - Kenya', 'template': 'raw'} {'additional_translations': {}, 'value': 876, 'label': 'Name of the institution(s) which facilitated the documentation/ evaluation of the Technology (if relevant)', 'text': 'Alliance Bioversity and International Center for Tropical Agriculture (Alliance Bioversity-CIAT) - Kenya', 'template': 'raw'}

1.3 Conditions regarding the use of data documented through WOCAT

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

Yes

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?

Comments:

The technology has shown positive result (increased production) where it has been implemented. No adverse impacts have been reported.

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

Promotion of different trees for agroforestry [Kenya]

Promoting the values of different trees and their benefits in agroforestry contributes to increased adoption by farmers.

Compiler: William Akwanyi
03/20/2023 10:04 a.m.

2. Description of the SLM Technology

2.1 Short description of the Technology

Definition of the Technology:

Cross-slope barriers in the form of vegetative strips are established on sloping lands to reduce runoff velocity and prevent soil loss, thereby contributing to the conservation of soil, water, and plant nutrients.

2.2 Detailed description of the Technology

Description:

Vegetative cross-slope barriers are strips of perennial plants that are established along the contours of sloping lands. They act as soil and water conservation measures to reduce runoff velocity and consequently prevent soil loss. The strips are mostly between 0.3 m and 1.5 m wide and consist initially of one or two rows of plants. They slow down the speed of runoff during heavy rainfall. This facilitates infiltration, and eroded sediment in the runoff is trapped on the upslope side of the barriers. Hence, they contribute to the conservation of soil, water, and plant nutrients. The most used plants/ crops used in establishing vegetative cross-slope barriers are perennial erect grasses, including Brachiaria sp., napier grass (Pennisetum purpureum), and vetiver grass (Vetiver zizanioides). Depending on species (vetiver being an exception), vegetative cross-slope barriers can serve as important sources of fodder for livestock. Some farmers prefer to establish crops (e.g., bananas and pineapples) or trees and shrubs (e.g., (e.g., Calliandra calothyrus, Grevillea robusta or Sesbania sesban) as cross-slope barriers at appropriate spacing (depending on the tree/ shrub) to serve as windbreakers as well as providing additional measures to control soil erosion. Alternatively, these may be combined with grasses. These can also serve as important sources of food, fodder, fuel, and timber.

In establishing vegetative cross-slope barriers, the distance between the barriers is dictated by the slope of the land. The ProSoil project through Welthungerhilfe trained Community Resource Persons (CRPs) on how to survey contours using a line level. The CRPs by extension train farmers on how to measure slope for their fields and how to determine the distance between the barriers using a predetermined scale. Once established, minimal labour is required for maintenance. The main vegetation (grasses) must be harvested or cut back to a height of less than 0.5 m before planting a crop in the main field to prevent them from suppressing the crops through shading. The trees, and shrubs may need to be trimmed (coppiced) during the cropping period to allow adequate sunlight to reach the crops. The cut material can be collected and used as fodder or firewood as appropriate or be incorporated during land preparation, or during weeding as mulch.

Farmers like the technology because it contributes to soil, water, and nutrient conservation and it reduces the steepness of the slope as soil eroded from the upper part of the slope accumulates on the upslope side of the barrier resulting, eventually, in distinct terrace-like benches. As a result, farmers find it easier to cultivate on these terraces. Vegetative cross-slope barriers can be associated with retention ditches, especially where farmers find it important to harvest the water. They can also provide firewood and fodder, especially where palatable cut and carry varieties of grass are used.

2.3 Photos of the Technology

Media Gallery

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

Country:

Kenya

Region/ State/ Province:

Kakamega County in western Kenya

Further specification of location:

Khalaba Ward, Matungu Sub-county in Kakamega County

Specify the spread of the Technology:

evenly spread over an area

If the Technology is evenly spread over an area, specify area covered (in km2):

0.003804

Is/are the technology site(s) located in a permanently protected area?

2.6 Date of implementation

Indicate year of implementation:

2019

2.7 Introduction of the Technology

Specify how the Technology was introduced:

as part of a traditional system (> 50 years)
through projects/ external interventions

Comments (type of project, etc.):

The technology has been practiced by some farmers in the past. The ProSoil project came in to improve on the farmers' knowledge about the technology and incorporated improvements in terms of slope measurements to determine where to locate the barriers on the farm.

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:

Yes

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

Agroforestry

Cropland

Annual cropping
Perennial (non-woody) cropping
Tree and shrub cropping

Annual cropping - Specify crops:

fodder crops - other
fodder crops - grasses
fodder crops - clover
oilseed crops - groundnuts
cereals - maize
legumes and pulses - beans
legumes and pulses - soya
root/tuber crops - cassava

Annual cropping system:

Maize/sorghum/millet intercropped with legume

Tree and shrub cropping - Specify crops:

fodder trees (Calliandra, Leucaena leucocephala, Prosopis, etc.)
avocado
fruits, other
mango, mangosteen, guava

Number of growing seasons per year:

Specify:

Crops are grown during the long and short rain seasons.

Is intercropping practiced?

Yes

If yes, specify which crops are intercropped:

Cereals intercropped with legumes.

Is crop rotation practiced?

Yes

If yes, specify:

Some of the plots are fallowed to allow soil regeneration.

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?

Yes

If yes, specify:

Manure from livestock is applied to the soil. Crops used on the slope barriers are fodder for livestock.

Products and services:

economic security, investment prestige
milk
manure as fertilizer/ energy production
eggs
meat

Species:

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

Count:

Species:

poultry

Count:

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

3.5 SLM group to which the Technology belongs

agroforestry
integrated crop-livestock management
cross-slope measure

3.6 SLM measures comprising the Technology

vegetative measures

V1: Tree and shrub cover
V2: Grasses and perennial herbaceous plants

3.7 Main types of land degradation addressed by the Technology

soil erosion by water

Wt: loss of topsoil/ surface erosion
Wg: gully erosion/ gullying

3.8 Prevention, reduction, or restoration of land degradation

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

prevent land degradation
reduce land degradation

Comments:

Reducing land degradation (soil erosion) is a secondary objective of the technology.

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

4.1 Technical drawing of the Technology

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Technical specifications (related to technical drawing):

Length of the farm (down the slope): 120 m
Width of the farm (along the contour): 31.7 m
Number of vegetative cross-slop barriers established: 6
Width of barriers: ranges between 0.3 m and 0.5 m
Slope: 4%
Width of the established terraces/ distance between any two barriers: 24 m
Plants used: brachiaria and napier grass (grasses), grevillea and calliandra (trees and shrub), bananas (crops)
1st barrier on the upper side (F) is on a retention ditch
Last barrier (A) is on the upper side of a channel that collects excess runoff and prevents damage to neighbours' farms on the lower side of the farm

Author:

William Akwanyi

Date:

17/02/2023

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:

0.00761 ha

If using a local area unit, indicate conversion factor to one hectare (e.g. 1 ha = 2.47 acres): 1 ha =:

1 ha = 2.47 acres

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 =:

124.21352

Indicate average wage cost of hired labour per day:

250

4.3 Establishment activities

	Activity	Timing (season)
1.	Contour surveying to establish locations for the vegetative cross slope barriers	Before planting
2.	Planting	After rains

4.4 Costs and inputs needed for establishment

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

8000.0

If land user bore less than 100% of costs, indicate who covered the remaining costs:

The ProSoil project through Welthungerhilfe purchased grass splits and tree seedlings for the farmer(s) and covered the cost of contour surveying.

4.5 Maintenance/ recurrent activities

	Activity	Timing/ frequency
1.	Weeding	After every harvest
2.	Adding manure/ compost	After every harvest
3.	Regular inspection to fill large gaps in the barriers that are 30 Cm or more by replanting	Monthly during the rainy season

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

	Specify input	Unit	Quantity	Costs per Unit	Total costs per input	% of costs borne by land users
Labour	Weeding	Man-days	3.0	250.0	750.0	100.0
Labour	Adding manure/ compost	Man-days	2.0	250.0	500.0	100.0
Equipment	Hoe (jembe) for weeding	No.	1.0	90.0	90.0	100.0
Equipment	Wheelbarrow for carrying manure/ compost	No.	1.0	500.0	500.0	100.0
Equipment	Spade for scooping manure/ wheelbarrow	No.	1.0	100.0	100.0	100.0
Fertilizers and biocides	Manure/ compost	Wheelbarrows	20.0	50.0	1000.0	100.0
Total costs for maintenance of the Technology					2940.0
Total costs for maintenance of the Technology in USD					23.67

Comments:

Vegetative cross-slope barriers are productive; hence, the costs are balanced by very quick returns.

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

The stated costs are estimates.

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

Specify average annual rainfall (if known), in mm:

1200.00

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:

Kakamega Meteorological Station

Agro-climatic zone

humid

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:

not relevant

Comments and further specifications on topography:

Farmer's field slope is 4%. Hence, the barriers were spaced 24 m from each other.

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%)

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?

Is flooding of the area occurring?

5.5 Biodiversity

Species diversity:

high

Habitat diversity:

medium

Comments and further specifications on biodiversity:

The area has high agrobiodiversity since 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:

> 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:

youth
middle-aged

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

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

Land ownership:

individual, not titled
individual, titled

Land use rights:

individual

Water use rights:

open access (unorganized)
individual

Are land use rights based on a traditional legal system?

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

Quantity before SLM:

Quantity after SLM:

Comments/ specify:

Quantity refers to the number of 90 Kg bags of maize produced per acre. Although vegetative cross-slope barriers reduced the available space for crops, other SLM technologies such as retention ditches and the use of compost contributed to the increase in the production. According to the farmer, the soil at the farm was highly eroded before the SLM technologies were introduced.

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 cross-slope barriers were established.

fodder production

decreased

increased

Comments/ specify:

the farmer estimates that the amount of napier grass harvested from the farm within a year has increased. Farmer not able to quantify.

fodder quality

decreased

increased

Comments/ specify:

Not easy to quantify but according to the farmer, napier grass is doing better compared to how it was before the cross-slope barriers were established.

animal production

decreased

increased

Quantity before SLM:

Quantity after SLM:

Comments/ specify:

Amount of milk produced by one cow during early lactation period.

land management

hindered

simplified

Comments/ specify:

Easy of working on less eroded soils. A farmer's estimate.

Income and costs

expenses on agricultural inputs

increased

decreased

Quantity before SLM:

5000

Quantity after SLM:

Comments/ specify:

Expenditure on fertilizer in KES. The farmer no longer uses fertilizer.

farm income

decreased

increased

Quantity before SLM:

Quantity after SLM:

6000

Comments/ specify:

The farmer earns income from selling napier grass - per year. This is based on the farmer's estimate.

diversity of income sources

decreased

increased

Comments/ specify:

The farmer considers the money earned from selling napier grass as an extra source of income.

Socio-cultural impacts

food security/ self-sufficiency

reduced

improved

Quantity before SLM:

Quantity after SLM:

0.5

Comments/ specify:

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 the farmer's estimate.

SLM/ land degradation knowledge

reduced

improved

Comments/ specify:

Level of knowledge in SLM/ land management. This is a farmer's estimate that she has increased her knowledge in SLM.

Ecological impacts

Water cycle/ runoff

surface runoff

increased

decreased

Comments/ specify:

The farmer notes that the amount of water leaving the farm and silting other farms in the lower areas. has greatly reduced.

Soil

soil loss

increased

decreased

Comments/ specify:

the farmer notes that the amount of silt deposited in the lower parts of the farm and in other farms on the lower side of the farm has reduced.

soil accumulation

decreased

increased

Comments/ specify:

the farmer notes that the amount of soil trapped by the vegetative cross slope barriers is high and this leads to an increase in soil accummulation at the farm.

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

damage on neighbours' fields

increased

reduced

Comments/ specify:

Amount of runoff leaving the farm with potential to cause soil erosion in neighbouring farms.

Specify assessment of off-site impacts (measurements):

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

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

Gradual climate change

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

Climate-related extremes (disasters)

Meteorological disasters

	How does the Technology cope with it?
local rainstorm	well

6.4 Cost-benefit analysis

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

Short-term returns:

very 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

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?

6.7 Strengths/ advantages/ opportunities of the Technology

Strengths/ advantages/ opportunities in the land user’s view
Soil erosion control.
increased yields.

Strengths/ advantages/ opportunities in the compiler’s or other key resource person’s view
More benefits, including firewood and other products from trees planted on the cross slope barriers.

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

Weaknesses/ disadvantages/ risks in the compiler’s or other key resource person’s view	How can they be overcome?
Reduces area meant for crop production.	Ensure optimum use of manure to offset production loss.

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

One online source reviewed.

When were the data compiled (in the field)?

17/02/2023

7.3 Links to relevant online information

Title/ description:

Vegetative Barriers for Erosion Control

URL:

https://extension.missouri.edu/publications/g1653

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, etc.
2. Some of the impacts (section 6) cannot be quantified.

Links and modules

Collapse all

Links

Promotion of different trees for agroforestry [Kenya]

Promoting the values of different trees and their benefits in agroforestry contributes to increased adoption by farmers.

Compiler: William Akwanyi
03/20/2023 10:04 a.m.

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