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

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)

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

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

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

3.1 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

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

Comments:

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

3.7 Main types of land degradation addressed by the Technology

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.

4.1 Technical drawing of the Technology

4.2 General information regarding the calculation of inputs and costs

Specify how costs and inputs were calculated:

• per Technology area

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

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

5.1 Climate

5.2 Topography

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

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

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

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

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

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

Comments:

The above rating varies from one village to the other.

6.1 On-site impacts the Technology has shown

Socio-economic impacts

Production

Income and costs

Socio-cultural impacts

Ecological impacts

Water cycle/ runoff

Soil

Biodiversity: vegetation, animals

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

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)?

How do the benefits compare with the maintenance/ recurrent costs (from land users' perspective)?

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.

7.1 Methods/ sources of information

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.