Stabilisation of irrigation channels in sandy soils with old rice bags and Pandanus plants [Cambodia]

បច្ចេកទេសដាក់បាវខ្សាច់ និងដាំដើមរំចេកតាមភ្លឺស្រែជាទំនប់ទប់ការហូរច្រោះ (Khmer)

technologies_1650 - Cambodia

Completeness: 82%

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)

SLM specialist:
SLM specialist:

Khun Lean Hak



SLM specialist:

Pith Khonhel



Name of the institution(s) which facilitated the documentation/ evaluation of the Technology (if relevant)
Society for Community Development in Cambodia (SOFDEC) - Cambodia
Name of the institution(s) which facilitated the documentation/ evaluation of the Technology (if relevant)
Local Agricultural Research and Extension Centre (LAREC) - Cambodia

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:


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?


2. Description of the SLM Technology

2.1 Short description of the Technology

Definition of the Technology:

In sandy areas, old rice bags are filled with sand and piled up as dikes bordering irrigation channels, and Pandanus plants are used to stabilize them on the long term.

2.2 Detailed description of the Technology


The paddy fields are surrounded by dikes and fed by local temporary streams and irrigation channels, as well as by rain. In sandy soils the dikes around the irrigation channels and fields cannot hold the water due to erosion. Old rice bags are filled with sand and piled up to form stable dikes on the short term, and Pandanus suckers are planted every 0.5 – 1 m to ensure a stability on the long term due to the root system.

The purpose of the dikes, stabilized for short and long term, is to ensure the flow of water to the paddy fields by reducing the riverbank erosion. It also helps to keep the water in the paddy fields. The Pandanus can be used to make mats and baskets, although this use diminishes due to the low cost of plastic. After a few years, the Pandanus on the dike is tall and spiky enough to fence off cattle and protect the rice from grazing.

To stabilize 50 m of dike, around 100 old rice bags are filled with sand and piled up on a height of 2 bags. Pandanus suckers are planted on the water side, between the bags, and sand is used to cover the plants and bags. Poles and sticks are used to stabilize the bags and plants until the root system is established. This is done in the beginning of the rainy season to ensure the growth of the sucker. In the first year, after each rain the eroded sand has to be added back to the dike. After the establishment phase, from the second year on, the Pandanus have to be cut back as they grow quickly and can grow tall.

The analysed area is flat (slope < 2%), with a tropical climate (dry season from November to May and wet season from June to October), and the soils are mostly sandy or loamy. The soil has a low fertility, contains little organic matter, and acidifies. The area has been deforested a long time ago, and the groundwater table is rather high (1-2 m during the dry season, on the surface during wet season).
Due to climate change, farmers notice more erratic rainfall, temperature rises and more recurrent droughts. Rice is the predominant crop grown in the area, since it serves as staple food (mix subsistence and commercial activities). Cattle are usually grazing on the fields after the harvest, without much control. Thus the cattle grazes too often and too much on the same spot, leading to degradation.
The increasing migration rate (the young generation leaves the villages to work in the cities, garment industry or abroad) results in a decrease of available labour force in the area which has detrimental effects on the agricultural activities. Furthermore, the civil war in the 1970s (Khmer Rouge) led to the loss of agricultural knowledge. Several NGOs are trying to re-establish the knowledge.

2.3 Photos of the Technology

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



Region/ State/ Province:

Kampong Chhnang

Further specification of location:

Chrey Bak/Rolea Pha’ear

Specify the spread of the Technology:
  • evenly spread over an area
If precise area is not known, indicate approximate area covered:
  • 1-10 km2

Traditionally the irrigation channels were stabilized with sticks and some fences (old sugar palm leaves roofs…) This is changing now, as old rice bags become available.

2.6 Date of implementation

If precise year is not known, indicate approximate date:
  • more than 50 years ago (traditional)

2.7 Introduction of the Technology

Specify how the Technology was introduced:
  • as part of a traditional system (> 50 years)
Comments (type of project, etc.):

The use of Pandanus plants to stabilise the irrigation channels and dikes is a traditional setting in the area. The use of rice bag is a newer setting.

3. Classification of the SLM Technology

3.1 Main purpose(s) of the Technology

  • create beneficial economic impact
  • create beneficial social impact

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



  • Annual cropping
Annual cropping - Specify crops:
  • cereals - rice (wetland)
Number of growing seasons per year:
  • 1

Longest growing period in days: 210, Longest growing period from month to month: June to December

Waterways, waterbodies, wetlands

Waterways, waterbodies, wetlands


Major land use problems (compiler’s opinion): low soil fertility, overgrazing, lack of irrigation
Major land use problems (land users’ perception): lack of irrigation, low soil fertility
Livestock is grazing on crop residues

3.4 Water supply

Water supply for the land on which the Technology is applied:
  • mixed rainfed-irrigated

3.5 SLM group to which the Technology belongs

  • irrigation management (incl. water supply, drainage)
  • water diversion and drainage
  • surface water management (spring, river, lakes, sea)

3.6 SLM measures comprising the Technology

vegetative measures

vegetative measures

  • V1: Tree and shrub cover
structural measures

structural measures

  • S3: Graded ditches, channels, waterways

3.7 Main types of land degradation addressed by the Technology

soil erosion by water

soil erosion by water

  • Wr: riverbank erosion
water degradation

water degradation

  • Ha: aridification

Main causes of degradation: soil management (Lack of organic matter), labour availability (Factory work in garment industry)
Secondary causes of degradation: crop management (annual, perennial, tree/shrub) (mainly annuals are planted in monocultures (rice)), overgrazing (free ranging of cattle)

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

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

4.1 Technical drawing of the Technology

Technical specifications (related to technical drawing):

Next to a road, (left) there is an irrigation channel in sandy soil. To prevent the little dam next to the rice field (right) from eroding, old rice bags are filled with sand and piled up. Between the rice bags, Pandanus suckers are planted. Sometimes they are also used to stabilise roadsides (not shown in this picture).
Kampong Chhnang
Date: 2014

Technical knowledge required for field staff / advisors: low
Technical knowledge required for land users: low
Main technical functions: stabilisation of soil (eg by tree roots against land slides), water harvesting / increase water supply, sediment retention / trapping, sediment harvesting

Vegetative measure: On dikes, allong irrigation channels
Vegetative material: T : trees / shrubs
Vertical interval within rows / strips / blocks (m): 0.5 - 1 m
Vegetative measure: Vegetative material: T : trees / shrubs
Trees/ shrubs species: Pandanus grown from suckers

Bund/ bank: graded
Height of bunds/banks/others (m): 0.3
Width of bunds/banks/others (m): 0.75

Construction material (other): Sand and sandbags
Vegetation is used for stabilisation of structures.


Stefan Graf, Switzerland

4.2 General information regarding the calculation of inputs and costs

other/ national currency (specify):


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


Indicate average wage cost of hired labour per day:


4.3 Establishment activities

Activity Timing (season)
1. Fill the old rice bags with sand, pile them up, stabilize with sticks and add more sand after each rain, till the root system of the Pandanus plants have established (1 year) Beginning of wet season (Jun/Jul)
2. Plant the Pandanus suckers between the bags beginning of wet season (June/July)

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
Fertilizers and biocides Construction of biodigester 1.0 400.0 400.0 50.0
Total costs for establishment of the Technology 400.0
Total costs for establishment of the Technology in USD 0.1

Duration of establishment phase: 12 month(s)

4.5 Maintenance/ recurrent activities

Activity Timing/ frequency
1. Maintain the dikes every rainy season
2. Cut back the Pandanus plants Once a year, before planting rice

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 labour 1.0 121.5 121.5 100.0
Total costs for maintenance of the Technology 121.5
Total costs for maintenance of the Technology in USD 0.03

Machinery/ tools: showel, knife, Shovel, knife
The costs were calculated in 2014 for 50 m of dike (50 m = 1 unit). To protect an irrigation channel of a 50 m, 100 m of dike would be needed, as the dikes would be on both sides.

4.7 Most important factors affecting the costs

Describe the most determinate factors affecting the costs:

The labour is the most costly part in this technology. Through the use of old rice bags filled with sand the costs are already reduced.

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:

1486.45 mm 2013 in Kampong Chhnang

Agro-climatic zone
  • sub-humid

Thermal climate class: tropics. 27° to 35°C

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%)
  • 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):
  • coarse/ light (sandy)
Topsoil organic matter:
  • medium (1-3%)
  • low (<1%)

5.4 Water availability and quality

Ground water table:

on surface

Availability of surface water:


Water quality (untreated):

poor drinking water (treatment required)

Comments and further specifications on water quality and quantity:

during wet seasons

5.5 Biodiversity

Species diversity:
  • low

5.6 Characteristics of land users applying the Technology

Market orientation of production system:
  • subsistence (self-supply)
  • mixed (subsistence/ commercial)
Off-farm income:
  • 10-50% of all income
Relative level of wealth:
  • average
  • rich
Individuals or groups:
  • individual/ household
  • women
  • men
Indicate other relevant characteristics of the land users:

Land users applying the Technology are mainly common / average land users
Population density: 10-50 persons/km2
Annual population growth: 0.5% - 1%
Off-farm income specification: handicraft, remittances and factory work

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:
  • communal/ village
  • individual, not titled
Land use rights:
  • communal (organized)
  • individual
Water use rights:
  • open access (unorganized)

land users have a title which is not recognized by the state

5.9 Access to services and infrastructure

  • poor
  • moderate
  • good
  • poor
  • moderate
  • good
technical assistance:
  • poor
  • moderate
  • good
employment (e.g. off-farm):
  • poor
  • moderate
  • good
  • poor
  • moderate
  • good
  • 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


crop production

Comments/ specify:

Dried residues are put in the garden (cucumber, pumpkin, watermelon) which increases nutrient availability.

fodder production


risk of production failure


production area


energy generation

Comments/ specify:

Before the installation of the biogas system, the land user bought firewood.

Income and costs

expenses on agricultural inputs

Comments/ specify:

He saves 50 $ on chemical fertilizer per year.

farm income


diversity of income sources




Socio-cultural impacts

food security/ self-sufficiency


health situation

Comments/ specify:

No smoke from open fire.

contribution to human well-being

Comments/ specify:

On the long term livelihood is improved, because he saves over 60 $ per year in firewood and battery charging for light, as well as 50 $ for chemical fertilizer.

Ecological impacts

Water cycle/ runoff

water quantity


water quality

Comments/ specify:

Pollution of groundwater due to washing out of nutrients.


soil moisture


soil loss


soil organic matter/ below ground C

Comments/ specify:

Most of the carbon is transformed into methane, not available as organic matter.

Biodiversity: vegetation, animals

pest/ disease control

Other ecological impacts

Reduced weed seeds

Comments/ specify:

Compost usually not completely decomposed, as well as raw manure, contain lots of weed seeds.

6.2 Off-site impacts the Technology has shown

groundwater/ river pollution

Comments/ specify:

Sludge is left to dry outside, nutrients washed out into groundwater. Not measurable.

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 known
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 known

Other climate-related consequences

Other climate-related consequences
How does the Technology cope with it?
reduced growing period well

6.4 Cost-benefit analysis

How do the benefits compare with the establishment costs (from land users’ perspective)?
Short-term returns:


Long-term returns:


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

very positive

Long-term returns:

very positive


Difficult question for farmers.

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?
  • 91-100%

100% of land user families have adopted the Technology without any external material support
The farmers guessed that around 10 % of the land users use this technology in the area. There is a moderate trend towards spontaneous adoption of the Technology
The sandbags reduce the labour, thus are used more and more even though they cost.

6.7 Strengths/ advantages/ opportunities of the Technology

Strengths/ advantages/ opportunities in the land user’s view
The Pandanus leaves are used for baskets and mats.
The water is stored in the rice fields. Without stabilisation, the berms would not hold any water at all in sandy conditions.
Cattle is fenced off the rice fields through tall and thick (old) Pandanus plants growing on the dikes.
The irrigation channels are not eroded, water keeps flowing

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?
The Pandanus grow too quickly and too tall, and require workload which is not available. Select slow growing species or individuals.
Rodents use the Pandanus as niches. Protect natural predators (snakes), or hunt/trap the rodents.
Weaknesses/ disadvantages/ risks in the compiler’s or other key resource person’s view How can they be overcome?
the plastic from the rice bags disintegrates with time and causes river pollution. Use organic material (e.g. rice bags) to stabilize the dike for the first year.

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)?


7.2 References to available publications

Title, author, year, ISBN:

NBP National Biodigester Program

Available from where? Costs?

Title, author, year, ISBN:

Lam et al. 2009. Domestic Biogas Compact Course. University of Oldenburg.

Available from where? Costs?

Title, author, year, ISBN:

Gurung. 2009. Review of Literature on Effects of Slurry Use on Crop production. The Biogas Support Program

Links and modules

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