Stabilisation of irrigation channels in sandy soils with old rice bags and Pandanus plants [Cambodia]
- Creation:
- Update:
- Compiler: Stefan Graf
- Editor: –
- Reviewers: Deborah Niggli, Alexandra Gavilano, Rima Mekdaschi Studer
បច្ចេកទេសដាក់បាវខ្សាច់ និងដាំដើមរំចេកតាមភ្លឺស្រែជាទំនប់ទប់ការហូរច្រោះ (Khmer)
technologies_1650 - Cambodia
- Full summary as PDF
- Full summary as PDF for print
- Full summary in the browser
- Full summary (unformatted)
- Stabilisation of irrigation channels in sandy soils with old rice bags and Pandanus plants: Feb. 28, 2017 (inactive)
- Stabilisation of irrigation channels in sandy soils with old rice bags and Pandanus plants: March 11, 2019 (inactive)
- Stabilisation of irrigation channels in sandy soils with old rice bags and Pandanus plants: Feb. 7, 2024 (public)
View sections
Expand all Collapse all1. 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
SOFDEC/LAREC, www.sofdec.org
Cambodia
SLM specialist:
Pith Khonhel
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:
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?
No
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
Description:
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
Country:
Cambodia
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
Comments:
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.
Map
×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
Cropland
- Annual cropping
Annual cropping - Specify crops:
- cereals - rice (wetland)
Number of growing seasons per year:
- 1
Specify:
Longest growing period in days: 210, Longest growing period from month to month: June to December
Waterways, waterbodies, wetlands
Comments:
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
- V1: Tree and shrub cover
structural measures
- S3: Graded ditches, channels, waterways
3.7 Main types of land degradation addressed by the Technology
soil erosion by water
- Wr: riverbank erosion
water degradation
- Ha: aridification
Comments:
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.
Author:
Stefan Graf, Switzerland
4.2 General information regarding the calculation of inputs and costs
other/ national currency (specify):
Riels
If relevant, indicate exchange rate from USD to local currency (e.g. 1 USD = 79.9 Brazilian Real): 1 USD =:
4000.0
Indicate average wage cost of hired labour per day:
5.00
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 |
Comments:
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 |
Comments:
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%)
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.
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:
good
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
Gender:
- 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)
Comments:
land users have a title which is not recognized by the state
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
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
workload
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
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:
positive
Long-term returns:
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:
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%
Comments:
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)?
29/08/2014
7.2 References to available publications
Title, author, year, ISBN:
NBP National Biodigester Program
Available from where? Costs?
www.nbp.org.kh
Title, author, year, ISBN:
Lam et al. 2009. Domestic Biogas Compact Course. University of Oldenburg.
Available from where? Costs?
http://www.nbp.org.kh/publication/study_report/2_domestic_biogas%20.pdf
Title, author, year, ISBN:
Gurung. 2009. Review of Literature on Effects of Slurry Use on Crop production. The Biogas Support Program
Links and modules
Expand all Collapse allLinks
No links
Modules
No modules