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Intercropping of eggplants between mango trees using rice straw mulching to reduce evaporation [Cambodia]

Growing eggplant under mango trees

technologies_2255 - Cambodia

Completeness: 88%

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)

Official of Chetr Borei district office of agriculture, forestry and fisheries:

Ly Saravuth

(+855) 89 796 786) / n/a / n/a

Chetr Borei district office of agriculture, forestry and fisheries

Khsar village, Dar commune, Chetr Borei district, Kratie


Acting chief of Preaek Prasab District Office of Agriculture, Forestry and Fisheries:
land user:

Yarn Sopheak

(+855)17 834 572 / n/a

n/a / n/a


Kamboa village, Kou Loab commune, Chetr Borei district, Kratie



Name of project which facilitated the documentation/ evaluation of the Technology (if relevant)
Scaling-up SLM practices by smallholder farmers (IFAD)
Name of the institution(s) which facilitated the documentation/ evaluation of the Technology (if relevant)
Royal University of Agriculture (RUA) - Cambodia

1.3 Conditions regarding the use of data documented through WOCAT

When were the data compiled (in the field)?


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:

Intercropping of eggplants between mango trees and the application of straw mulching on the plants’ roots and the land so as to retain soil moisture by reducing heat-induced evaporation. When the rice straw rots, it provides organic matter and makes soil less compact. The farmer can benefit from the short-term crop for a period of three years before the mango trees fully produce fruits.

2.2 Detailed description of the Technology


Intercropping of a short term crop between the fruit trees which are the long term crop (mango trees which will provide fruit in their third year depending on the species variety and maintenance) is a best agroforestry practice which provides both economic and environmental benefits. When the mango trees are still young and have not yet produced fruit, there is also free space between the trees. In order to gain additional benefits and to avoid weeds growing that could be harmful to the mango trees, the growing of eggplants with rice straw mulching could provide co-benefits in the form of maintaining, weed control, watering, and the application of fertilizer for the mango trees. The eggplants could produce fruit within three months after having been planted and they can be harvested for several months in a year. In this way farmers can generate income for their daily expenditure before the mango trees produce fruit. By using this technology, farmers are able to improve their livelihoods compared with before.

In this SLM technology, the mango trees, eggplants and mulched rice straw interact beneficially. In the dry season, the trees provide some shade for the eggplants and the rice straw on the eggplants' roots and land helps retain soil moisture reducing evaporation, and this prevents the crops from withering during hot days. In addition, when the farmer waters the eggplant,it also provides water to the trees. In rainy season, the rice straw and the eggplants act as an important vegetation cover for the prevention of soil erosion through surface run-off during heavy rainfall. Besides the rice straw and its decayed materials are a crucial food source for micro-organisms in the soil that improve the cycling of nutrients and the soil less compact, enabling a better growth of the crops.

In this technology, the mango trees are planted in row with an interval of six metres and the eggplants are transplanted among the rows of trees ensuring that there is a distance of one metre between each plant within a row, and a distance of 1.5 metres between one row and another. The pit for each mango tree is 70x70x70cm and a mixture of burned rice husk, cow manure and woody herb is added as fertilizer in the bottom of the pit. When planting, the compost or slurry from the of the bio-digester is also mixed in with the soil. Eggplant seedlings are transplanted in 10-cm holes using 20-30 day-old seedlings. Then the farmer applied rice straw mulching on the roots of eggplant and mango trees' roots and applied on the free space of the land. The transplanted eggplants are watered on a daily basis, while the watering of the mango trees is carried out twice per week.
Weeding is done regularly so that the weeds do not absorb too many nutrients from the soil even there is no much weed. The farmer applies compost twice a year, usually once at the beginning of the rainy season in May, and also in October.

When the eggplants start to produce fruit, it takes around one hour for the farmer to harvest the crop on a daily basis. Weeding is sometimes carried out during the harvest. It is suggested that one should consider a rotation of short-term crops in order to maximize the benefits of this SLM technology, because growing one type of crop could absorb exact the same nutrients from the soil so the second crop growing are not very good and could cause disease outbreak on the crop. The rotation of crops in this case could include eggplants, mung beans, sweet corn or cucumbers. However it should examining the market demands as well.

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:

Kamboa village, Kou Loab commune, Chetr Borei district, Kratie

Further specification of location:



This technology is practiced on a crop land behind the house.

2.6 Date of implementation

Indicate year of implementation:


2.7 Introduction of the Technology

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

The farmer used to join a field visit to Battambang province supported by SNV in CHAIN project coordinated by Chetr Borei District Office of Agriculture, Forestry and Fisheries.

3. Classification of the SLM Technology

3.1 Main purpose(s) of the Technology

  • improve production
  • reduce, prevent, restore land degradation
  • create beneficial economic impact
  • Obtaining economic benefits from the short-term crops while the mango is not ready to produce fruits, and the rice straw helps reduce evaporation maintaining soil moisture.

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



  • Annual cropping
  • Tree and shrub cropping
  • Short-term crops
Main crops (cash and food crops):

Mango (producing fruits after 3 years) and eggplant (getting harvest after a month and continue for several months)

Mixed (crops/ grazing/ trees), incl. agroforestry

Mixed (crops/ grazing/ trees), incl. agroforestry

  • Agroforestry
Main products/ services:

Mango and eggplant

If land use has changed due to the implementation of the Technology, indicate land use before implementation of the Technology:

Degraded forest

3.3 Further information about land use

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

Pond and wells, but the wells went dry in 2016.

Number of growing seasons per year:
  • 1

Mango is a long-term crop, eggplant (4 months), sweet corn (2 months), mung bean (2 months)

Livestock density (if relevant):

19 cows and the manure is used in biodigester production

3.4 SLM group to which the Technology belongs

  • agroforestry
  • improved ground/ vegetation cover
  • integrated soil fertility management
  • Rice straw helps keep soil moisture and it become organic fertilizer when decays

3.5 Spread of the Technology

Specify the spread of the Technology:
  • evenly spread over an area
If the Technology is evenly spread over an area, indicate approximate area covered:
  • < 0.1 km2 (10 ha)

Land area for applying the technology is 35 x 70 m = 2450 square meter.

3.6 SLM measures comprising the Technology

agronomic measures

agronomic measures

  • A1: Vegetation/ soil cover
  • A2: Organic matter/ soil fertility
  • A3: Soil surface treatment
vegetative measures

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

soil erosion by water

  • Wt: loss of topsoil/ surface erosion
chemical soil deterioration

chemical soil deterioration

  • Cn: fertility decline and reduced organic matter content (not caused by erosion)
physical soil deterioration

physical soil deterioration

  • Pc: compaction
  • Pu: loss of bio-productive function due to other activities
biological degradation

biological degradation

  • Bc: reduction of vegetation cover
  • Bl: loss of soil life
  • Bp: increase of pests/ diseases, loss of predators
water degradation

water degradation

  • Ha: aridification

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

In this area, the soil has low fertility. The use of compost from the biodigester and rotating the short-term crops helps improve soil quality.

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

4.1 Technical drawing of the Technology


Vanny Om and Sophea Tim



4.2 Technical specifications/ explanations of technical drawing

The technology contains the 25 total planted mango trees and 350 eggplants.​ The area of applying this technology is 600 square meters( width 15 meters and length 40 meters).

4.3 General information regarding the calculation of inputs and costs

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

600 square meter

If using a local area unit, indicate conversion factor to one hectare:

1 hectare = 10,000 square meters

other/ national currency (specify):

Khmer Riel

Indicate exchange rate from USD to local currency (if relevant): 1 USD =:


Indicate average wage cost of hired labour per day:

30,000 Riel

4.4 Establishment activities

Activity Type of measure Timing
1. Ploughing the soil to sun dry Agronomic May
2. Digging the pits for mango trees Structural May
3. Applying the mixture of cow manure, burned rice hush and tree leaves in the pits Agronomic May
4. Planting the mango trees Agronomic May
5. Applying compost Agronomic June
6. Prepare the soil to grow the crops Structural June
7. Digging holes and transplant eggplant Agronomic June
8. Spreading the rice straw Agronomic June

4.5 Costs and inputs needed for establishment

Specify input Unit Quantity Costs per Unit Total costs per input % of costs borne by land users
Labour Ploughing the soil to sun dry Day 0.5 20000.0 10000.0 100.0
Labour Digging the pits for mango trees Pit 35.0 5000.0 175000.0 100.0
Labour Applying fertilizers Day 0.5 20000.0 10000.0 100.0
Plant material Mango trees Tree 25.0 8000.0 200000.0 100.0
Plant material Eggplant seeds Bag 1.0 8000.0 8000.0 100.0
Fertilizers and biocides lime kg 25.0 2000.0 50000.0 100.0
Fertilizers and biocides Compost from bidigester Tank 50.0 2000.0 100000.0 100.0
Construction material Hoe Piece 2.0 20000.0 40000.0 100.0
Construction material Carriers Paire 1.0 7000.0 7000.0 100.0
Construction material Soil digger Piece 1.0 25000.0 25000.0 100.0
Total costs for establishment of the Technology 625000.0

The farmer pays for the expense to create the technology using his own saving, the compost is own produced from the biodigester, which was supported by a project.

4.6 Maintenance/ recurrent activities

Activity Type of measure Timing/ frequency
1. Check the crops regularly Management Once every 5 days
2. Soil preparation after each short-term crop's harvest Agronomic After harvest
3. Making small pit around the mango tree Management Dry season
4. Apply compost Agronomic May and October
5. Watering the crops Agronomic Daily especially in dry season
6. Purchase pumping machine Management After growing mango trees

The pumping machine costs 1,600,000 Riel

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

If possible, break down the costs of maintenance according to the following table, specifying inputs and costs per input. If you are unable to break down the costs, give an estimation of the total costs of maintaining the Technology:



The pumping machine costs 1,600,000 Riel.

4.8 Most important factors affecting the costs

Describe the most determinate factors affecting the costs:

Cost of mango trees and pumping machine.

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:


Specifications/ comments on rainfall:

In 2015 the annual rainfall is 1138.2 mm, in 2014 is 1696.50, in 2013 is 1661.8 mm.

Indicate the name of the reference meteorological station considered:

Department of Meteorology, Ministry of Water Resources and Meteorology (2015)

Agro-climatic zone
  • sub-humid

There are two seasons: dry and rainy seasons

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.
Indicate if the Technology is specifically applied in:
  • not relevant

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):
  • fine/ heavy (clay)
Topsoil organic matter:
  • low (<1%)
If available, attach full soil description or specify the available information, e.g. soil type, soil PH/ acidity, Cation Exchange Capacity, nitrogen, salinity etc.

In the past, this area was degraded forest. Soil quality is low and contains some stone. After using compost and apply the technology the soil quality has been improved.

5.4 Water availability and quality

Ground water table:

5-50 m

Availability of surface water:


Water quality (untreated):

good drinking water

Is water salinity a problem?


Is flooding of the area occurring?


Comments and further specifications on water quality and quantity:

Groundwater in this area contains some minerals, so the farmer store it in a pond before irrigating to the crops. Rainwater and tape water from other areas is the source of drinking water.

5.5 Biodiversity

Species diversity:
  • low
Habitat diversity:
  • low

5.6 Characteristics of land users applying the Technology

Sedentary or nomadic:
  • Sedentary
Market orientation of production system:
  • commercial/ market
Off-farm income:
  • > 50% of all income
Relative level of wealth:
  • rich
Individuals or groups:
  • individual/ household
Level of mechanization:
  • manual work
  • mechanized/ motorized
  • women
Age of land users:
  • middle-aged
Indicate other relevant characteristics of the land users:

He is 45 years old.

5.7 Average area of land owned or leased 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, titled
Land use rights:
  • individual
Water use rights:
  • individual

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

Quantity before SLM:

Degraded forest land

Quantity after SLM:

Crop cultivation using compost

Comments/ specify:

Increase production

crop quality

Quantity before SLM:

Intertiled land

Quantity after SLM:


Comments/ specify:

Good for health

animal production

Quantity before SLM:

30 cows

Quantity after SLM:

19 cows

Comments/ specify:

Some cows were sold to get money for house construction.

risk of production failure

Quantity before SLM:

No crops

Quantity after SLM:


Comments/ specify:

Crop rotation

product diversity

Quantity before SLM:


Quantity after SLM:


Comments/ specify:


land management

Quantity before SLM:

Degraded land

Quantity after SLM:

With crops

energy generation

Water availability and quality

drinking water availability


drinking water quality


water availability for livestock


water quality for livestock


irrigation water availability


irrigation water quality


demand for irrigation water

Quantity before SLM:

No crops

Quantity after SLM:

Annual crops

Comments/ specify:

The short-term crops need to be irrigated every day.

Income and costs

expenses on agricultural inputs

Comments/ specify:

The farmer has own biodigester

farm income

Comments/ specify:

Generating regular incomes from selling eggplant.

diversity of income sources



Comments/ specify:

Regular maintenance of the crops

Socio-cultural impacts

food security/ self-sufficiency

Comments/ specify:

Household consumption and selling the surplus

health situation

Comments/ specify:

Compost from bio-digester is good for both the producer and consumers.

recreational opportunities

Quantity after SLM:

Have ideas to grow more crops

Comments/ specify:

Having some trees; it is less hot.

Ecological impacts

Water cycle/ runoff

water quantity


water quality



Comments/ specify:

Rice straw mulching and shade of the mango trees


soil moisture

Comments/ specify:

Rice straw mulching

soil cover

Comments/ specify:

vegetation cover of the eggplant

soil crusting/ sealing


soil compaction

Comments/ specify:

Compost helps improve the soil structure.

soil organic matter/ below ground C

Biodiversity: vegetation, animals

invasive alien species


beneficial species

Comments/ specify:

Increased biodiversity

pest/ disease control

Climate and disaster risk reduction

flood impacts


drought impacts


impacts of cyclones, rain storms



Comments/ specify:

Having some trees

6.2 Off-site impacts the Technology has shown

There are some people following this practice.

Comments/ specify:

There are some people come to visit and learn the practices.

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 Type of climatic change/ extreme How does the Technology cope with it?
annual temperature increase moderately
seasonal temperature dry season increase very well
seasonal rainfall wet/ rainy season decrease well
other gradual climate change Variation in rainfall pattern increase moderately

Climate-related extremes (disasters)

Meteorological disasters
How does the Technology cope with it?
local rainstorm moderately
Climatological disasters
How does the Technology cope with it?
heatwave moderately
drought well
Biological disasters
How does the Technology cope with it?
epidemic diseases well
insect/ worm infestation moderately

6.4 Cost-benefit analysis

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


Long-term returns:

very positive

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

slightly positive

Long-term returns:



While the mango has not produce fruits, harvest is don with the short-term crops.

6.5 Adoption of the Technology

  • 1-10%
Of all those who have adopted the Technology, how many have did so spontaneously, i.e. without receiving any material incentives/ payments?
  • 0-10%

6 households want to generate more incomes

6.6 Adaptation

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


If yes, indicate to which changing conditions it was adapted:
  • climatic change/ extremes
other (specify):

Rice straw mulching reduces evaporation

6.7 Strengths/ advantages/ opportunities of the Technology

Strengths/ advantages/ opportunities in the land user’s view
Possibility to grow other crops with the mango trees.
When watering the eggplants, it also benefits the mango trees.
Strengths/ advantages/ opportunities in the compiler’s or other key resource person’s view
The land is used effectively as it will take at least three years before the mango trees start to provide a harvest.
Rice straw helps to retain soil moisture, reduces evaporation and improves nutrient cycling.
Generation of a substantial income for the family.
The soil is not degraded by growing short term crop, crop rotation and using cow manure, composting and slurry from biodigester.

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?
Some carterpillars could damage the eggplants Manually pick off the insects' eggs and do not apply pesticide which could cause health risks
Insecure market demand; while eggplants are in peak production Try to access various markets and sale mobile at households.
Weaknesses/ disadvantages/ risks in the compiler’s or other key resource person’s view How can they be overcome?
When the mango trees are quite mature could not grow eggplant between trees. Select short-term crops that only need a smaller amount of light such as turmeric galanga.
Require compost and a biodigester Promote animal husbandry including cows, pigs and poultry.

7. References and links

7.1 Methods/ sources of information

  • field visits, field surveys

6 persons

  • interviews with land users

1 person

Links and modules

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