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

Growing eggplant under mango trees

technologies_2255 - Cambodia

Completeness: 84%

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

Chetr Borei district office of agriculture, forestry and fisheries


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

Yarn Sopheak



Chief of District Office of Agriculture, Forestry and Fisheries, Sambo:
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

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:


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):


If precise area is not known, indicate approximate area covered:
  • < 0.1 km2 (10 ha)

This technology is practiced on a crop land behind the house.
Land area for applying the technology is 18m x 30 m = 540 square meter.

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

Land use mixed within the same land unit:


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



  • Annual cropping
  • Perennial (non-woody) cropping
  • Tree and shrub cropping
Annual cropping - Specify crops:
  • cereals - maize
  • legumes and pulses - beans
  • eggplant
Annual cropping system:

Vegetables - wheat/barley/oat/upland rice

Perennial (non-woody) cropping - Specify crops:
  • flower crops - perennial
Tree and shrub cropping - Specify crops:
  • mango, mangosteen, guava
Number of growing seasons per year:
  • 1

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

Is intercropping practiced?


Forest/ woodlands

Forest/ woodlands


Mango is a long-term crop, eggplant (4 months), sweet corn (2 months), mung bean (2 months)
Livestock density: 19 cows and the manure is used in biodigester production and slurry from biodigester is used for cultivation crops. Those number of cows are enought for biodigester production everyday.

3.3 Has land use changed due to the implementation of the Technology?

Has land use changed due to the implementation of the Technology?
  • Yes (Please fill out the questions below with regard to the land use before implementation of the Technology)
Forest/ woodlands

Forest/ woodlands


Degraded forest

3.4 Water supply

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

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

3.5 SLM group to which the Technology belongs

  • agroforestry
  • improved ground/ vegetation cover
  • integrated soil fertility management

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

Technical specifications (related to technical drawing):

The technology contains the 25 total planted mango trees and 350 eggplants. The area of applying this technology is 540square meters( width 18 meters and length 30 meters).


Vanny Om and Sophea Tim



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:

540 square meter

other/ national currency (specify):

Khmer Riel

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:

30,000 Riel

4.3 Establishment activities

Activity Timing (season)
1. Ploughing the soil to sun dry May
2. Digging the pits for mango trees May
3. Applying the mixture of cow manure, burned rice hush and woody herb in the pits May
4. Planting the mango trees May
5. Applying slurry from biodigester on the plant roots. June
6. Prepare the soil mixing with cow manure, apply lime to grow the crops. June
7. Digging holes and transplant eggplant June
8. Spreading the rice straw June

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 Ploughing the soil to sun dry Peson-day 0.35 30000.0 10500.0 100.0
Labour Digging the pits for mango trees Peson-day 5.8 30000.0 174000.0 100.0
Labour Applying fertilizers and lime Peson-day 0.35 30000.0 10500.0 100.0
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 biodigester Tank 50.0 2000.0 100000.0 100.0
Construction material Hoe Piece 2.0 20000.0 40000.0 100.0
Construction material Handle basket 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
Total costs for establishment of the Technology in USD 156.25

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.

4.5 Maintenance/ recurrent activities

Activity Timing/ frequency
1. Check the crops regularly to make sure the crops not fall down or demage by insects. Once every 5 days
2. Soil preparation after each short-term crop's harvest After harvest
3. Making small pit around the mango tree When mango tree getting bigger
4. Apply compost and fertilzer KCL(15-15-15) May and October
5. Watering the crops Daily especially in dry season
6. Purchase water pumping machine After growing mango trees

The pumping machine costs 1,600,000 Riel

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:



The pumping machine costs 1,600,000 Riel.

4.7 Most important factors affecting the costs

Describe the most determinate factors affecting the costs:

The cost of water pumping machine is high, cost of mango trees and eggplant seeds, cost of hiring labor to plough the soil. But she doesn't expend on buying fertilizer because she use her own cow manure.

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 was 1138.2 mm, in 2014 1696.50, in 2013 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 applying the technology the soil quality has 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 the crops. Rainwater and tap 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 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, 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

Comments/ specify:

Production is increased because in previous land no crops cultivation, but now there are more than one crop.

crop quality

Comments/ specify:

The quality of crop is improved by using animal manure and compost.

risk of production failure

Comments/ specify:

The risk of production failure is reduced due to having more than one crop. Before, the farmer had no crops so he had no crop production for selling on the market.

land management

Comments/ specify:

Before it is the infertile soil but after more crops is cultivated and using compost, the soil fertility is improved.

Water availability and quality

demand for irrigation water

Comments/ specify:

Crop cultivation under mango tree is needed watering everyday.

Income and costs

expenses on agricultural inputs

Comments/ specify:

The farmer has his own cows, so she could have cow manure as the natural fertilizer for the crops. In addition, she also has biodigester which could get the slurry to produce compost without buying fertilizer from supplier.

farm income

Comments/ specify:

Generating regular income from selling eggplant.

diversity of income sources

Comments/ specify:

There are short-term and long-term crops cultivation so it can generate annual and monthly income.


Comments/ specify:

Regular maintenance of the crops is needed.

Socio-cultural impacts

food security/ self-sufficiency

Comments/ specify:

Household consumption and selling.

health situation

Comments/ specify:

Compost from biodigester is good for both the producer and consumers.

recreational opportunities

Comments/ specify:

Having some trees provides shade, it is less hot and fresh air.

Ecological impacts

Water cycle/ runoff


Comments/ specify:

Due to rice straw mulching and shade of the mango trees.


soil moisture

Comments/ specify:

Due to rice straw mulching.

soil cover

Comments/ specify:

Due to vegetation cover as eggplant and mango trees.

soil compaction

Comments/ specify:

When the rice straw rots, it become organic fertilizer benefit to the soil. Moreover, cow manure and compost helps to improve the soil structure.

soil organic matter/ below ground C

Comments/ specify:

The rotten of rice straw, the application of cow manure and compost could increase the soil organic matter.

Biodiversity: vegetation, animals

beneficial species

Comments/ specify:

The beneficial species are increased through slurry from biodigester and application of animal manure. The land user notices to increase of earthworm, ant, termite, small frog etc.

pest/ disease control

Comments/ specify:

Pests still occur but not many.

Climate and disaster risk reduction

drought impacts

Comments/ specify:

Drought impacts is reduced due to rice straw mulching and shade from mango tree.

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 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 well
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 done with the short-term crops.

6.5 Adoption of the Technology

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

There are 6 households who want to adopt the practice to generate more income. Even if they cannot follow all activities they still select some activities from this technology to implement.

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
Specify adaptation of the Technology (design, material/ species, etc.):

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 crops, 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 mobile sale of the product at other people's 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

One specific location

  • interviews with land users

1 person

  • interviews with SLM specialists/ experts

3 people

When were the data compiled (in the field)?


Links and modules

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