men sarom, buntong borarin, hing thida, ly tyneth and ou...

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Men Sarom, Buntong Borarin, Hing Thida, Ly Tyneth and Ou Wenjun

Phnom Penh, Cambodia

June 2014

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EXECUTIVE SUMMARY

Cassava has become the second largest crop production in Cambodia and contributes substantially to the

country economy after rice. The expansion of cassava from a homestead crop to a commercial crop, and

to the second largest crop production in the country raised many concerns especially in its relation to

deforestation and about its impacts to the environment, particularly to soil structure and its nutrients. On

the other hand cassava processing produces large amount of wastes including solid and liquid which are

high in organic matter constituents and cyanide. If not properly managed, liquid (water) waste has the

potential to pollute ground water or lakes, rivers or streams into which it flows. Furthermore, cassava

processing wastes can also produce unpleasant smells and unattractive pictures.

The main objectives of this study are therefore to (i) assess to what degree cassava plantation has caused

soil erosion and the depletion of soil nutrients and soil organic matter (organic carbon), and identify

practical mitigation measures that can be adopted by small-scale farmers to sustain their cassava

production, (ii) document and quantify the recent expansion of areas under cassava cultivation relative

to other previous and current land uses including other cash crops, forest, and deforested areas. This

relates to concerns about the possible causal links between cassava production and deforestation, and

(iii) identify the current practices of different scale cassava processing plants in term of waste

management, assess the potential risks from this waste management on the environment and especially

on water resources, and identify the current proper waste management applied by the processors as well

as the technologies which are either presently available or under development for waste treatment and

management.

The study was conducted in two provinces, Kampong Cham and Pailin, using both quantitative and

qualitative approaches. In Kampong Cham, based on cassava planted areas, three districts, namely

Dambe, Memot and Tbaung Khmom were selected for the study, whereas in Pailin the study was

conducted in the districts of Pailin and Sala Krao. This study included individual surveys with cassava

farmers and processors; testing on soil nutrient content (NPK), pH and soil organic matter (SOM) and

on water quality through identifying pH, Total Dissolved Solids (TDS) and Total Organic Carbon

(TOC) in water sources close to the cassava processing plants.

Results from this study show that the majority of cassava farmers have less than 10 hectares of land

available for crop cultivation. The production can be found in two ecosystems: on flat and sloping land.

About half of the cassava growing is found on sloping land at the north west region of the country

including Pailin. The current practice by farmers on land preparation is regarded as inappropriate that

make cassava fields particularly the sloping land very susceptible to soil erosion especially if it is

associated with heavy rainfall. Adoption of new improved practices is needed to avoid soil erosion.

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There are no differences in soil nutrients as well as the level of pH, soil humidity and organic matter in

the areas under cultivation of cassava and those areas under the cultivation of other crops and wild

habitats. Despite the widespread belief that cassava takes excessive amount of nutrients from the soil

and can lead to soil nutrient depletion and soil erosion, this finding suggests that cassava has a similar

nutrient withdrawal from the soil as other crops. Reports by many authors also support the finding.

The expansion of cassava production probably resulted from changing the cropping system prioritized

by farmers based on market demand and crop productivity output rather than by claiming new forest

land as previously believed. In Kampong Cham, only about 10% of the interviewed farmers reported the

conversion of forest land to cassava plantation and no farmers in Pailin reported to have converted

forest land to cassava plantation. It is suspected that forest had been earlier cleared for commercial

purpose and/or for the production of other crops such as maize before it has been transferred to cassava.

Nevertheless, as forest data is not available or very difficult to be obtained a conclusive remark about

the effect of cassava production on deforestation cannot be drawn. It is suggested that this subject

should be further analysed in order to provide a clear picture on the relationship between cassava

expansion and deforestation.

There are three types of cassava processing plants in Cambodia: dried chip, dried starch and wet starch

processing. Cassava processing produces big quantity of solid and liquid wastes that can have negative

impact to the environment and human health. Through their strong and unpleasant smell, wastewater

and solid wastes can cause a hostile environment for farming communities living nearby. The analysis

of water samples collected from the water courses nearby the processing plants indicated that the levels

of Total Dissolved Solids (TDS) and Total Organic Carbon (TOC) are much higher than the standard

value for household consumption. In addition, the aesthetic and beauty of the environment is also

substantially affected by cassava processing if they are not properly managed. Unless these wastes are

treated properly and well protected from leaking to the water stream in the areas, the use of water

originated from those areas for drinking and/or cooking should be avoided.

More than 50 per cent of cassava processing managers recognize the problems arising from their

processing wastes and for that reason most of the processing plants have already set up their own waste

management structure. However, it appears that since most of the structures do not follow technical

specifications, they are prone to flooding during the rainy season and current waste processing

procedures produce a strong and unpleasant smell for the nearby villages. During flooding, wastewater

that is contained in each pond is often discharged freely into rice fields or other open water sources in

the area.

It is recognized that newly developed waste management technologies are available in the country, but

they are more suitable for larger scale rather than for small and medium cassava processing plants

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which are still struggling to keep their business going. Limited access to those new technologies, lack of

relevant information on newly developed waste management technology and lack of confidence of

processing managers on developed technologies are considered the main barrier for developing eco-

friendly cassava processing industry in the country.

To overcome those constraints, technical support from relevant departments and institutions, and an

appropriate enforcement of existing national codes of conducts on waste management are necessary.

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TABLE OF CONTENTS

Executive Summary ……………………………………………………………………….. 2

Acronyms and Abbreviation ……………………………………………………………… 6

Introduction ………………………………………………………………………………... 7

Methodology ………………………………………………………………………………. 9

Results and Discussions …………………………………………………………………… 11

1. Assessing degree of soil erosion and the depletion of soil nutrients and soil organic

matter (organic carbon), and identification practical mitigation measures that can

be adopted by small-scale farmers to sustain their cassava production

11

• General situation of cassava production and its trend ………………………… 11

• Composition of soil nutrients and soil organic matters in soil planted to

cassava and other crops ………………………………………………………. 17

2. Expansion of areas under cassava cultivation relative to other previous and current

land uses including other cash crops, forest, and deforested areas ………. 23

3. Current practices of different scale cassava processing plants in term of waste

management. ……………………………………………………………………… 25

• General situation of cassava processing plants and their waste management 25

• Cassava dries chip processing ………………………………………………... 26

• Cassava dried starch processing …………………..………………………….. 27

• Cassava wet starch processing ……………………………………………….. 30

• Impact of cassava processing wastes on environment ………………………. 31

• Awareness of cassava processors on waste management and their constraints

in adopting new management ………………………………………………… 36

Conclusion ………………………………………………………………………………… 38

Recommendations…………………………………………………………………………. 40

Mitigation measures to sustain the country cassava production ……………………… 40

Sustainable utilization and management of cassava processing wastes………………. 43

References ………………………………………………………………………………… 44

Appendices ………………………………………………………………………………… 46

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ACRONYMS AND ABBREVIATIONS

CARDI Cambodian Agricultural Research and Development Institute

CIAT International Centre for Tropical Agriculture

GDA General Directorate for Agriculture

K Potassium

KCl Potassium chloride

MAFF Ministry of Agriculture, Forestry and Fisheries

MOE Ministry of Environment

MofCOM Ministry of Commerce of China

N Nitrogen

NGO Non-Governmental Organization

NPK Nitrogen, Phosphorus and Potassium

OM Organic matter

P Phosphorus

PDA Provincial Department of Agriculture

RUA Royal University of Agriculture

SOM Soil organic matter

TDS Total Dissolved Solids

TOC Total Organic Carbon

UNDP United Nations for Development Programmes

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INTRODUCTION

Cassava (Manihot esculenta Crantz) is the second largest crop production in Cambodia after rice. It is

grown mainly by smallholder farmers for food to supplement the rice diet, for animal feed and for

extraction of starch from its roots. At the recent years there has also been major interest in the use of

cassava as a raw material for the production of ethanol.

Traditionally cassava production in Cambodia was only a farmstead crop production that is grown

mainly on the farmer backyard. However, the situation changed. For the last 10 year cassava production

area in Cambodia expanded exponentially from less than 30 thousand hectares in 2004 to more than 400

thousand hectares in 2013 (MAFF, 2005-2013). Cassava is cultivated in almost all provinces in the

country, but major production is found in Kampong Cham, Battambang, Pailin, Kratie, and Kampong

Thom where cassava production areas range from 20 thousand hectares in Pailin to almost 70 thousand

hectares in Kampong Cham (MAFF, 2013).

The expansion of cassava from a homestead crop to a commercial crop, and to the second largest crop

production in the country raised many concerns especially in its relation to deforestation. It was reported

that in 1960 Cambodia's forests covered 73% of the total land area of the country. This forest coverage

decreased dramatically to 58 per cent in 1999 with the annual deforestation rate between 1993-97

estimated at 140,000-175,000 ha (MOE, 2002). It is believed that the reduction has been attributed

mainly to commercial logging and agricultural encroachment.

There are contradicted reports about the impacts of cassava growing to the environment, particularly on

soil structure and its nutrients. It is widely believed that, cassava is known to cause serious soil

degradation due to excessive uptake of nutrients leading to soil nutrient depletion, or by causing serious

soil erosion when grown on slopes.

In contrary, research has shown that cassava extracts less nutrients from the soil than most other food

crops (Howeler, 1991; Charoenrath et al., 2012) that makes cassava to be grown in areas with low soil

fertility where other crops cannot be grown productively. However as it is true for all crops when

cassava is grown continuously on the same land without inputs of manure or fertilizers, soil nutrients

will eventually be depleted and productivity will decline (Howeler, 1991; Charoenrath et al, 2012). This

is undeniable as even without growing any crop, the soil fertility will naturally decline by nutrient

leaching and erosion, particularly in the case of sandy soil texture. Finding has suggested that, soils

planted to cassava are particularly susceptible to erosion during the initial stage of the crop before the

canopy closes and rain impacts directly on the soil (Putthacharoen et al., 1998). To alleviate the

problem, in some areas bush-fallow rotations are used to maintain availability of soil nutrients for the

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next crop, but where such rotations are not possible, farmer apply animal or green manures, or chemical

fertilizers to maintain yields.

Cassava processing produces large amount of wastes including solid and liquid which are high in

organic matter constituents and cyanide. Solid wastes are mainly derived from cassava chip processing,

if properly managed, can be utilized in many ways in crop and animal productions. Liquid (water) waste

on the other hand has the potential to pollute ground water or lakes, rivers or streams into which it

flows. Cassava processing can also produce unpleasant smell and unattractive pictures. Due to all these

problems, cassava processing has always been regarded with a reputation of a major environment

pollutant.

However, there has been little reported study on extents of environmental concerns caused by both

cassava production and processing, and how to alleviate the problem to an acceptable level. The main

objectives of this study are therefore:

a) Assessing to what degree cassava plantation has caused soil erosion and the depletion of soil

nutrients and soil organic matter (organic carbon), and identifying practical mitigation measures

that can be adopted by small-scale farmers to sustain their cassava production.

b) Documenting and quantifying the recent expansion of areas under cassava cultivation relative to

other previous and current land uses including other cash crops, forest, and deforested areas.

This relates to concerns about the possible causal links between cassava production and

deforestation, the value and efficacy of utilizing cleared land for cassava cultivation, and the

wider issue of agricultural zonation.

c) Identifying the current practices of different scale cassava processing plants in term of waste

management, assessing the potential risks from this waste management on the environment and

especially on water resources, and identifying the current proper waste management applied by

the processors as well as the technologies which are either presently available or under

development for waste treatment and management.

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METHODOLOGY

Within the framework of the Cambodia-China-UNDP South-South Cooperation on Cassava Project

funded by the Chinese Ministry of Commerce (MofCOM), managed by UNDP Cambodia and the

Cambodian Ministry of Agriculture, Forestry and Fisheries, a study on environmental impact

assessment was carried out by a team from the Royal University of Agriculture. The study was

conducted in two provinces of Kampong Cham (Tbaung Khmom) and Pailin using both quantitative and

qualitative approaches. In Kampong Cham, based on cassava planted areas, three districts of Dambe,

Memot and Tbaung Khmom were selected for the study, whereas in Pailin the study was conducted in

the districts of Pailin and Sala Krao (Appendix 2). This study included surveys with cassava farmers and

processors, and testing on soil nutrient content (NPK), pH and soil organic matter (SOM) and on water

quality through identifying pH, Total Dissolved Solids (TDS) and Total Organic Carbon (TOC) in water

sources closed to the cassava processing plants.

1. Survey- there were two types of surveys: (1) cassava production history and practices in selected

location, and (2) waste management practiced by different level of cassava processors (small,

medium and large). For the first type of survey, 20 cassava farmers in each district were selected

for interviewing. That is 100 farmers in total selected for interviewing in the study

(Questionnaires attached: Appendix 2). This survey focused on:

- History of cassava production in the region: when and why

- Production practices: how to grow, application of fertilizer and pesticides, experience and

management of soil erosion, physically, mode of harvesting, and trend of cassava production

in the study areas.

For the waste management survey, a total of 41 cassava processors were selected for the study

(Questionnaires attached: Appendix 3). The focus of this survey was:

- Identification of different types of wastes produced by different levels of cassava processors

- Assessment of the processors’ understanding about the hazards of the wastes to human

health and surrounding environment including water sources in the surrounding areas, and

their waste management

2. Soil test- horizontal analysis of soil nutrient, pH and SOM were analyzed. Soil samples from the

areas under cultivation of cassava of not less than 3 years were taken for laboratory testing. The

same procedure was applied for those areas in close proximity with cassava plantation but

planted to other crops (cassava never planted in that area for at least 5 years), and also those

areas where forest or natural habitats are present. Sampling was conducted in two horizontal

layers- the topsoil (0-20cm) and at 30 to 50 cm depth. A total of 120 testing samples were taken

for laboratory testing on the availability of total nitrogen (N), phosphorus (P), and potassium

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(K), pH and the availability of soil organic matter (SOM). Sampling was taken from 3 cassava

growing districts in Kampong Cham (Dambe, Memot and Tbaung Khmom), and two districts in

Pailin. Five composite samplings in any location were mixed to constitute one testing sample.

3. Water quality test – 70 Samples of water sources (open well, deep well, pond or river) located in

close proximity to cassava processing plants were collected and sent to laboratory for testing on

pH, total dissolved solids (TDS) and the amount of total organic carbon (TOC) in the water.

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RESULTS AND DISCUSSIONS

1. Assessing degree of soil erosion and the depletion of soil nutrients and soil organic matter

(organic carbon), and identification practical mitigation measures that can be adopted by

small-scale farmers to sustain their cassava production.

1.1 General situation of cassava production and its trend in Kampong Cham and Pailin

There were 100 cassava farmers randomly selected for this study. Amongst them 60 farmers are

from Kampong Cham and, 40 farmers are from Pailin. More than half of the farmer interviewees were

male, about 40 per cent have never attended any school about the same percentage have attended

primary classes and only 16-17 percent have high school degree (Table 1).

Table 1 Distribution of famers on gender and educational background

Kampong Cham Pailin

Respondent % Respondent %

Educational background

• Never attended 25 42 15 38

• Primary 25 42 18 45

• Secondary 10 16 7 17

• University 0 0 0 0

Gender of interviewee

• Male 33 55 25 62

• Female 27 45 15 38

More than 50 per cent of cassava plantation in Kampong Cham is cultivated on flat land and only 42 per

cent on sloping land. In Pailin, the situation is contrarily different from Kampong Cham, where 90 per

cent of cassava production is practiced on sloping areas (Table 3). Results of this study indicated

however that, in both Kampong Cham and Pailin, cassava is predominantly cultivated in the areas where

the slope is less than 30 degree and only in few isolated occasions where it is practiced in the area which

is steeper than 45 degree (Table 3).

This study also shown that, despite the production of cassava from 42 per cent to 90 per cent is

practiced on sloping land (Table 3), most farmers do plough the land up-down the slope (Table 4).

Result indicates that we have less than 36 per cent of farmers who prepare the land by contour and up to

80 per cent of farmers do prepare the land up and down the slope (Table 4). This latter practice can have

a very negative impact to the soil as it makes the land very susceptible to soil erosion especially if it is

associated with heavy rainfall. According to Howeler (2012) soil erosion is a function of rainfall, soil

structure, length and gradient of the slope, crop and management factors. Therefore this poor crop

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management could accelerate soil erosion in the area if this disturbing situation is not corrected on time.

Results from the survey have indicated that 16 farmers (17 per cent) in Kompong Cham and 10 farmers

(22 per cent) in Pailin reported of the problem they have come across with soil erosion on their cassava

plantation (Table 8).

Due to time limitations, quantifying soil erosion was difficult, but there are reports from many research

studies in the region that confirm a strong association between cassava productions in sloping land on

soil erosion (Howeler, 1991; Tongglum et al.; 1998, Vongkasem et al., 2000; Putthacharoen et al.

,1998; Suyamto and Howeler, 2004; Nguyen Dinh Kiem, 1989). According to Nguyen Dinh Kiem

(1989) cassava cultivation as monoculture gave a level of erosion of 145.1 t/ha/year that is significantly

higher than planting tea (33.3 t/ha/year), pine forest (28.7t/ha/year) and natural grass (12 t/ha/year).

Despite the quantity of the soil erosion being rather lower in their study, Suyamto and Howeler (2004)

reported that farmers practice (up-and-down ridging) produce a high level of erosion (11.81 t/ha) in

comparison with other cultural practice in cassava-based cropping systems in Indonesia.

Table 3 Topography of the areas planted to cassava

Topography Kampong Cham Pailin

Correspondent Share (%) Correspondent Share (%)

Flat 35 58 4 10

Slope 25 42 36 90

• Gentle slope (< 150) 10 40 20 55

• Medium (150-300) 8 32 10 28

• Steep (300-450) 5 20 2 6

• Very steep (>450) 2 8 4 11

Table 4 Land preparation practices by cassava farmers where the crop is planted in sloppy land.

Kampong Cham Pailin

Respondent Frequency (%) Respondent Frequency (%)

Plowing by contour 9 36 6 17

Plowing up and down of

the slop

16 64 30 83

Total 25 100 36 100

The majority of farmers in both provinces have less than 10 ha of land for cassava plantation (Table 5).

In Kampong Cham, famers do plant the crop directly without raising a bed but it is contrary to Pailin

where raising bed for cassava production is most common (Table 6). Differences in this practice are

probably influenced by differences in weather conditions of the two provinces where the study is taken.

Based on weather data over many years, it is obvious that rainfall in Kampong Cham is between 1200 to

1400 mm, which is less than the average rainfall in Pailin where it can range from 1600 to 1800 mm. In

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the area where rainfall is high, the construction of a bed is important in order to protect the crop from

flooding especially at the early stages of plant growth. This study also indicates a (possible) relationship

between rainfall pattern and planting method which can be horizontally (180 degree) or vertically (45-

90 degree). Result from this study has shown that most farmers in Kampong Cham prefer to plant the

crop horizontally (180 degree), whereas in Pailin, where the average rainfall in high, vertical planting is

more common (Table 6).

Table 5 Size of cassava plantation and percentage of farmer holding from 60 respondents in Kampong

Cham and 40 in Pailin.

Size of cassava plantation Frequency (%)

Kampong Cham Pailin

Less than 5 ha 62 45

Less than 10 ha 99 83

Less than 20 ha - 98

Less than 50 ha - 100

Less than 100 ha -

Less than 300 ha 100

Table 6 Cassava production practices.

Kampong Cham Pailin

Respondent Frequency (%) Respondent Frequency (%)

Raised bed 12 20 39 98

No bed 48 80 1 2

Planting vertical (900) 4 7 34 85

Planting horizontal (1800) 56 93 6 15

Spacing 50 x 150 cm 27 45 9 23

Spacing 100 x 100 cm 17 28 1 2

Spacing (others specify: 80x 80

cm,80x 100cm, 70x 70 cm 16 27 30 75

For the last 5 years, cassava productions trends in both provinces have indicated a declining yield (Table

7). In Kampong Cham yield declined from as high as 30.5 tons in a hectare before 2010 to less than 20

tons in 2013 (38 per cent decline). In Pailin, the situation is very similar: cassava root yield continuously

dropped from about 50 tons before 2010 to less than 30 tons of root yield in 2013 (42 per cent decline).

Causes for yield decline are presented in Table 8. Based on results presented in Table 8, it clearly

suggests that in Kampong Cham, where more than 50 per cent of the production is on flat land (Table

3), the main reasons for yield decline include weed problems, soil fertility decline and erosion, damages

caused by pests and diseases, the use of poor planting materials and heavy rainfall. In Pailin, where

more than 90 per cent of the production is on sloping land, excessive rain, erosion and declining soil

fertility and, poor planting materials are blamed for yield decline (Table 8).

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Table 7 Cassava Root yield (T/ha) for the last 5 years of cassava plantation.

Year Kampong Cham Pailin

Yield (T/ha) Standard

Deviation

Yield (T/ha) Standard

Deviation

2013 18.9 7.8 29.5 9.0

2012 25.8 27.9 36.4 12.0

2011 24.6 8.1 38.0 18.7

2010 27.2 9.0 42.0 18.7

Before 2010 30.5 10.9 50.6 21.1

Table 8 Reasons for yield decline in cassava production

Reasons Kampong Cham Pailin


1 Weed problems 14 15 4 9

2 Soil erosion and soil

fertility declines

16 17 10 22

3 Insects and diseases 23 24 2 4

4 Stem and tuber of cassava

are destroys

3 3 4 9

5 Hot weather and too

much rains

12 13 11 24

6 Poor planting materials 11 12 5 11

7 No respond 15 16 9 20 Note: Respondent can provide more than one answers.

The majority of surveyed farmers (65-95 per cent) in both provinces have indicated that they never use

fertilizer in their cassava production (Table 10). It is understandable that upland soils in both provinces

where cassava is cultivated, classified as Kampong Siem, O’Riang Eu and Labansiek soil group which

are considered rich in soil nutrients (CARDI, 2009; CARDI, 2011; Bell et all, 2007; Seng vang et al.,

2007). Nevertheless, due to lack of nutrient replacement especially in the case where cassava is

continuously cultivated in the same area for many years, soil fertility certainly decline and consequently

lower cassava root yield. Therefore reduction in yield for the last 5 years (Table 8) could have resulted

from overexploitation of land resources where substantial quantities of nutrients are taken from the

field. This finding is supported by earlier studies. According to Howeler (2012), continuously planting

crops without fertilizer resulted in yield decline in all crops as nutrients are removed from the field in all

plant parts. As noted by Nguyen Tu Siem (1992), continuous cropping of upland rice and cassava

without fertilizer resulted in zero yield in the fourth crop cycle for upland rice, while cassava still

produced about 40 per cent of its first year yield.

While there is no formal research on the links between pests and diseases and cassava production,

results from this study confirm their presence and the damage that they can cause to cassava crop yields

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(Tables 8 & 14). All farmers in both provinces ought to apply pesticides, in order to save their cassava

crop from being damaged by pests and diseases (Table 10). The use of pesticides on cassava production

especially if it is not under technical recommendation brings another negative impact to the

environment and human health. It is important therefore that this practice should be properly checked

and interventions should be promptly organized. There are other ways of managing crop damage by

pests and diseases. For instant, uses of resistant varieties, healthy planting materials and natural

biological agents are considered the other effective measures against pests and diseases but unlike the

use of chemical pesticides, these latter measures have no negative impact to the environment and human

wellbeing and also feasible or economic option for low-income farmers (Howeler, 2014, CARDI, 2012).

.

Table 10 Fertilizer and pesticides uses in cassava production.

Kampong Cham Pailin


Fertilizer application

• Use 21 35 2 5

• Never use 39 65 38 95

Pesticides application

• Use 47 78 39 98

• Never use 13 22 1 1

With only 2 isolated cases in Pailin, cassava is manually harvested and the harvested roots are sold

directly to the traders without prior cleaned by any type of water (Tables 11 and 12). More than 99 per

cent of cassava roots sold is in the form of fresh roots with only 1-2 per cent is in the form of dried chip

(Table 12). Minimal involvement of machine harvester in cassava production plus no use of water to

clean the harvested roots is a positive sign in soil conservation strategy. Generally it is believed that the

combination of these two management practices, machine harvester and water cleaning can cause

serious soil erosion at the harvesting time.

Table 11 Harvesting in cassava production.

Kampong Cham Pailin


Harvesting

• Machine harvester 0 0 2 5

• By hand 60 100 38 95

Cleaning

• Yes 0 0 0 0

• No 60 100 40 100

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Table 12 Sale of cassava products

Kampong Cham Pailin

Quantity (Ton) % Quantity (Ton) %

Year 2012

• Fresh roots 1467.5 99 8450.0 >99

• Dried chip 19.5 1 38.5 <1

Year 2013

• Fresh roots 1461.0 99 8294.3 96

• Dried chip 10.0 1 341.7 4

Note: Figures presented in this table are sum from all participated farmers in the survey.

Table 13 Cassava contribution to the household economy

Year Kampong Cham (%) Pailin (%)

Cassava Rice Others Cassava Rice Others

2013 70 15 15 76 0 24

2012 71 15 14 76 0 24

2011 74 14 12 70 0 30

2010 76 13 11 66 0 34

Before 2010 79 11 10 55 0 45

Cassava production in both provinces is facing insecurity unless all the constraints raised by famers are

solved (Table 14). In both provinces, Kampong Cham and Pailin, more than 60-70 percent of farmers

considered yield decline which is due to pests and diseases damage, and damage caused by drought and

flood, as the main constraints in their cassava production. Availability of labor is also raised by farmers

in both provinces, but it appeared that the problem is more serious in Pailin (35 per cent) then in

Kampong Cham (8 per cent). It is true that labor availability is becoming a major issue in all crop

production systems, including cassava, and this can be more critical if the production is to be expanded.

As Cambodia is solely dependent on international market for cassava products, any fluctuation in

cassava demand in the international market, particularly Chinese market, can have strong influence to

the local market. This situation cannot be avoided unless direct trade deal with Chinese counterpart is

to be made and along with that cassava wet starch processing is to be expanded and its production is met

the required standard. If the situation cannot be solved the move to more profitable crops such as rubber

and black pepper cannot be excluded. This speculation can be confirmed in the Table 15 where about 40

per cent of famers in Kampong Cham are ready to move to other cropping system as due to the

constraints they are facing (Table 14) and only 32 per cent will stay in the cassava business. There is a

reversed trend in Pailin, where more than 67 percent of farmers in Pailin still prefer to stay with cassava

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regardless of the problems they are facing and only 3 per cent said they want to stop growing this crop

(Table 15).

Yield declines which are more likely resulted by pest damages and soil fertility decline, can be

overcome by technical support of field experts providing that there is such a program available.

Table 14 Constraints in cassava production

Kampong Cham Pailin

Respondent Percentage Respondent Percentage

1 Availability of labor 4 8 14 35

2 Low price 7 14 0 0

3

Yield declined (Pest problems,

drought and too wet) 38 78 26 65

Table 15 Future plan

Kampong Cham Pailin


1 Stop growing cassava 24 40 1 3

2 Grow more cassava 19 32 27 67

3 Not sure 15 25 8 20

4 Any other reasons 2 3 4 10

1.2 Composition of soil nutrients and soil organic matters in soils planted to cassava and other crops

Soil samples from the areas under cultivation of cassava of not less than 3 years were taken for

laboratory testing. The same procedure was applied for those areas planted to other cash crops located

in close proximity to cassava plantation but has never been planted to cassava, and those areas where

forest or natural habitats are present. Sampling was conducted in two horizontal layers- the topsoil (0-

20cm) and the sub-soil at 30 to 50 cm depth. From each layer, a total of 60 testing samples were taken

for laboratory testing. From these 60 samples, 20 are from cassava production plot, 20 from cash crop

production areas and the remaining 20 from forest land. At each sample site five composite samplings

were mixed to constitute one testing sample. Analyses on the availability of totals nitrogen (N),

phosphorus (P), and potassium (K), pH and the availability of soil organic matter (SOM) was conducted

in a private Food and Chemical Services laboratory in Phnom Penh (Appendix 5). Results of laboratory

analysis are presented in Tables 16-19.

Results from soil profile study conducted in Kampong Cham and Pailin demonstrated that cassava

production in Cambodia is generally occupied in three major soil groups namely Kampong Siem,

O’Riang Eu and Labansiek (Bell et al, 2007; Seng et al., 2009). This finding is strongly supported by

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the earlier upland soil classification in Cambodia by the Cambodian Agricultural Research and

Development Institute (White et al., 1997; Seng et al., 2007). Details description of each soil types can

be found in Appendix 6.

Results from this study do not support the hypothesis that cassava production leads to the depletion of

soil nutrients. Based on soil nutrient analysis, when comparing soil nutrients of N, P and K between soil

samples, at both top-soil layer (0-20cm) and sub-soil layer (30-50cm), taken from cassava growing

areas and those samples taken from land areas under the production of other crops and wild habitat we

found no differences between them for either in Kampong Cham or Pailin. Similar situation is found if

we compare the level of pH, soil humidity and organic matter (OM).

In all cases, we have test statistics of t comparatively lower than its critical value, therefore we can

declare with confidence that the levels of soil nutrients in the areas under cultivation of cassava are no

statistically different from those under the cultivation of other crops or under wild habitats (Table 16-

18).

Results from the analysis of soil samples collected from cassava production areas are contradicted to

general believes of high nutrient leaching in cassava cultivation but they are consistent with results

obtained from other studies. Nevertheless, this finding suggests the following:

• It is an indication that cassava has a similar nutrient withdrawal from the soil as compared to the

other crops. Earlier report presented by Howeler (1991) and Charoenrath et al. (2012) confirm

this finding as they came to the conclusion that cassava extracts even less nutrients from the soil

than most other food crops, and for that reason cassava can be grown in areas with low soil

fertility where other crops cannot be grown productively. Nevertheless, there has no earlier

report study on soil nutrients comparison between land of natural habitat and land planted to

cassava. It is very difficult however to make a general conclusion on nutrient withdrawal from

the soil as natural habitat consists of a diversity of different plant species, ranging from grasses,

bushes and trees, within any location and that can vary greatly between locations.

• In the common sense, natural forest soils are better in physical, chemical and biological

properties than agricultural soils. It can be true for some but not all. In our case, due to the

expansion of commercial and agricultural activities in the regions, there is no dense forest

nearby therefore degraded forest lands which are as much as natural grass land where soil

nutrients are easily degraded especially if this forest situates on sloping land were used (Picture

plate 1). Occasional application of fertilizers, chemical and/or organic, and tillage when the land

is cultivated could be the other factors that can help maintain soil properties in the agricultural

land as compare to neglected degraded forest land. Result of this study may also provide, other

Page | 19

than just a comparison with cassava planted land, a general picture of nutrient values of

degraded forest land.

Picture Plate 1. Wild habitat and degraded forest lands where soil samples were taken.

Tables 16 & 18 clearly show that the average content of nitrogen (N) in the soil surface of samples

taken from the three types of soils planted to cassava, to other crops and to forest are consistently

similar among them as well as between the provinces. In Kampong Cham the level of N ranges 1.29,

1.35 & 1.27 g/Kg dry weight for cassava planted soil, for other crops cultivation and for forest soil,

respectively. In Pailin, they are at a similar range of 1.32, 1.65 & 1.35 g/Kg dry weight, respectively.

There is also similarity (no significant difference) between the level of phosphorous (P) in any particular

province, but its level appears higher in Kampong Cham soils than in Pailin as it ranges of 0.44, 0.48,

0.34 vs 0.14, 0.13, 0.06 g/Kg dry weight respectively. This result may indicate that Kampong Cham

soils are rich in P as compared to Pailin. It is in a reversed situation for the level of potassium (K) as it

contains higher in Pailin than in Kampong Cham soils. There are also differences in pH and OM in both

provinces. According to this study, soil in Kampong Cham is more acidic (pH is around 5), whereas in

Pailin it is close to neutral (pH is around 6.30). Pailin Soil is also likely to have more organic matter

(OM) than in Kampong Cham soils (Table 20).

Results also indicate that at the sub-soil layer (30-50cm), there is lower in the content of N and poorer

OM as compared to the surface layer. There is no difference however between the levels of P, K and

soil humidity (Table 20).

Page | 20

Table 16 Nutrient contents of soils under cassava, other crop productions and forest habitat in Kampong

Cham

N (g/Kg DW) P (g/Kg DW) K (g/Kg DW)

Cassava Crops Forest Cassava Crops Forest Cassava Crops Forest

Top Soil (0-20cm)

Min 0.36 1.09 0.52 0.04 0.05 0.03 0.14 0.17 0.15

Max 3.47 1.96 3.93 1.44 1.16 1.37 0.95 0.29 0.38

Mean 1.29 1.35 1.27 0.44 0.48 0.34 0.31 0.20 0.24

Standard deviation 0.70 0.35 0.91 0.41 0.45 0.41 0.24 0.05 0.07

t-test (cassava vs crops) 0.80 0.86 0.10

Level of significance ns ns ns

t-test (cassava vs forest) 0.95 0.53 0.27


Sub Soil (30-50cm)

Min 0.36 0.34 0.32 0.04 0.05 0.03 0.14 0.14 0.14

Max 1.82 0.97 1.14 0.62 0.59 0.72 0.82 0.32 0.42

Mean 0.76 0.72 0.64 0.23 0.35 0.23 0.22 0.20 0.21






Table 17 Soil pH, humidity and organic matter (OM) of soils under cassava, other crop productions and

forest habitat in Kampong Cham

pH Soil humidity (g/100g) OM (g/100g DW)


Top Soil (0-20cm)

Min 3.93 4.40 4.16 2.99 9.36 3.06 1.26 2.40 1.39

Max 6.26 5.70 6.50 17.70 17.20 19.20 5.02 4.22 5.29

Mean 5.16 5.04 5.08 8.02 12.69 9.48 3.07 3.45 2.91






Sub Soil (30-50cm)

Min 4.16 4.30 3.93 6.81 10.70 6.13 0.87 0.83 0.67

Max 6.33 5.53 6.90 18.50 19.10 21.50 4.37 4.38 4.51

Mean 4.99 4.84 4.68 13.28 15.34 12.97 2.38 2.94 2.54






Page | 21

Table 18 Nutrient contents of soils under cassava, other crop productions and forest habitat in Pailin

N (g/Kg DW) P (g/Kg DW) K (g/Kg DW)


Top Soil (0-20cm)

Min 0.67 0.77 0.82 0.03 0.04 0.05 0.28 0.57 0.66

Max 1.89 3.11 1.88 0.27 0.28 0.06 0.99 2.28 1.41

Mean 1.32 1.65 1.35 0.14 0.13 0.06 0.55 1.20 1.04




t-test (cassava vs

forest)

0.96 0.00 0.41


Sub Soil (30-50cm)

Min 0.40 0.42 0.36 0.04 0.07 0.18 0.17 0.15 0.26

Max 1.76 1.51 1.19 0.39 0.21 0.24 0.93 1.19 1.24

Mean 0.86 0.95 0.78 0.13 0.12 0.21 0.41 0.55 0.75




t-test (cassava vs

forest)

0.87 0.12 0.61


Table 19 Soil pH, humidity and organic matter (OM) of soils under cassava, other crop productions and

forest habitat in Pailin

pH Soil humidity (g/100g) OM (g/100g DW)


Top Soil (0-20cm)

Min 5.70 5.96 6.36 2.48 1.67 5.30 3.03 3.67 3.64

Max 7.06 7.36 6.63 17.50 15.40 6.33 7.56 6.15 6.53

Mean 6.33 6.55 6.50 8.67 8.38 5.82 4.44 4.84 5.09






Sub Soil (30-50cm)

Min 5.66 5.06 6.03 9.49 7.30 7.01 2.87 3.02 2.49

Max 6.96 6.90 7.63 19.20 23.00 13.70 5.10 4.97 5.20

Mean 6.33 6.30 6.83 14.22 14.46 10.36 3.94 3.87 3.85






Page | 22

Table 20 Average soil nutrients and Soil pH, humidity and organic matter (OM) for both provinces

Nitrogen (g/Kg DW)

Phosphorous (g/Kg DW)

Potassium (g/Kg DW)

pH Humidity (g/100g)

OM (g/100g DW)

KC Pailin KC Pailin KC Pailin KC Pailin KC Pailin KC Pailin

Surface layer

• Cassava 1.29 1.32 0.44 0.14 0.31 0.55 5.16 6.33 8.02 8.67 3.07 4.44

• Other crops 1.35 1.65 0.48 0.13 0.20 1.20 5.04 6.55 12.69 8.38 3.45 4.84

• Forest 1.27 1.35 0.34 0.06 0.24 1.04 5.08 6.50 9.48 5.82 2.91 5.09

Average 1.30 1.44 0.42 0.11 0.25 0.93 5.09 6.46 10.06 7.62 3.14 4.79

Sub-soil

• Cassava 0.76 0.86 0.23 0.13 0.22 0.41 4.99 6.33 13.28 14.22 2.38 3.94

• Other crops 0.72 0.95 0.35 0.12 0.20 0.55 4.84 6.30 15.34 14.46 2.94 3.87

• Forest 0.64 0.78 0.23 0.21 0.21 0.75 4.68 6.83 12.97 10.36 2.54 3.85

Average 0.71 0.86 0.27 0.15 0.21 0.57 4.84 6.49 13.86 13.01 2.62 3.89

KC : Kampong Cham,

Page | 23

2. Expansion of areas under cassava cultivation relative to other previous and current land

uses including other cash crops, forest, and deforested areas.

The national data on major crop production areas have indicated a substantial increase in cassava

plantation along with a marginal increase of maize (Table 21). As shown in this Table 21, from 2010 to

2013 there was a new claimed land for agricultural production of 477, 229 ha, from which rice

cultivation claimed more than 50 per cent, followed by cassava (48 %) and maize (7%). On the other

hands, there was a reduction in soybean and mungbean production. It is not clear, how this agricultural

land could be increased in this substantial figure, but as suggested by MOE (2002), this could be

attributed to the encroachment on forest land through deforestation activities.

However, this study has shown that only 10 per cent of cassava farmers in Kampong Cham admitted

that the land they currently use for cassava plantation had recently been converted from a forest land

(Table 22). This was not even the case in Pailin where no farmer has reported of claiming forest land for

cassava production. Result of this study suggests that the expansion of cassava production areas is likely

resulted from changing crop cultivation as prioritized by farmers rather than by transforming forest

areas into cassava land. About 95 per cent of respondents in Pailin specified that they decided to change

from maize to cassava production (Table 22) because of economic reason, i.e cassava produces high

yield and therefore they can get higher income by growing this crop (Table 23). Similarly in Kampong

Cham, where 43 per cent of farmers indicated of their decision to change from soybean to cassava

farmers (Table 22), 35 percent of them agreed that cassava can provide higher yield and more income

for their family (Table 23).

It is obvious that the expansion of cassava production in these areas probably resulted from changing

cropping system prioritized by farmers based on market demand and crop productivity output rather

than by claiming new forest land as previously believed. This result clearly contradicts to a general

belief that a dramatic expansion of cassava production from less than 30 thousand hectares in 2004 to

more than 400 thousand hectares in 2013 (MAFF, 2005-2013) was a direct link to deforestation. It could

be possible that forest had been earlier cleared for the production of other crops such as maize before it

has been transferred to cassava.

Forest data is not available at all levels, district, provincial and national, therefore it is not possible to

make a conclusive remark on the effect of cassava production on deforestation.

Page | 24

Table 21 Areas under crop production in 2010 and 2013 and rate of their increase1)

Cultivated area (ha) Rate of increase (2013-2010)

2010 2013 Hectare %

Rice 2,795,892 3,052,420 256,528 53.8

Maize 205,070 239,748 34,678 7.3

Cassava 190,525 421,375 230,850 48.4

Soybean 101,904 80,688 - 21,216 - 4.4

Mungbean 66,265 54,312 - 11,953 - 2.5

Vegetables 49,873 52,449 2,576 0.5

Others2) 106,690 92,456 - 14,234 - 3.0

Total cropping areas (ha) 3,516,219 3,993,448 477,229 100

1)After MAFF Annual Report 2011 and 2014. 2). Including peanut, sugar cane, sweet potato, sesame, jute and tobacco

Table 22 Crops grown in the areas where is now planted to cassava

Crops grown before

change to cassava Kampong Cham Pailin

Respondent Share (%) Respondent Share (%)

Forest 6 10 0 0

Rubber 2 3 0 0

Maize 1 2 38 95

Soybean 26 43 1 2.5

Others 25 42 1 2.5

Table 23 Reasons for changing to cassava

Reasons Kampong Cham Pailin

Respondent Share (%) Respondent Share (%)

1 Cassava provides high yield and high

income and market demand 21 35 16 40

2 Cassava is easy to grow 3 5 5 12

3 follow their neighbors 8 13 0 0

4 Soybean is low yielding and low price 11 18 1 3

5 Rice cannot grow well 6 10 0 0

6 Have many land 2 3 0 0

7 Maize is low yielding and low income 0 0 10 25

8 Like to change the crop for rotation 1 2 5 12

9 Others 7 12 3 8

10 Not responded 1 2 0 0

Page | 25

3. Current practices of different scale cassava processing plants in term of waste

management. Assessing the potential risks from cassava processing waste management on the

environment and especially on water resources, and identifying the current proper waste

management applied by the processors as well as the technologies which are either presently

available or under development for waste treatment and management

3.1 General situation of cassava processing plants and their waste management

A total of 41 cassava processors were selected for this study. There were 23 in Kampong Cham and 18

in Pailin (Table 24). Despite there is a classification of enterprise based on their investment capital and

number of employee (Table 25 ), in practice this classification cannot be applied in the purpose of this

study for cassava processing plants. Therefore due to lack of information to classify the scale of

cassava processing plants and their availability to join the study, selection of samples for interviews

were based mainly on cassava related products. Those are the production of cassava dried chips, dried

starch, wet starch and semi-final product of cassava known as Sagu and Saray. Thirty one samples were

collected from dried chip processors, 3 from dry starch, 1 from wet starch and 6 from sagu and saray

processors. There are 8 processing plants, 5 in Kampong Cham and 3 in Pailin, that produce dried

starch, but among them only 3 were selected to this study.

Table 24 Type and number of samples selected for waste management survey

Type of processing plant Samples selected

Kampong Cham Pailin Total

Dried chips processors 14 17 31

Dry starch processors 02 01 03

Wet starch processors 01 - 01

Sagu and Saray processors 6 - 6

Total 23 18 41

Table 25: Classification of enterprise of Ministry of Industry and Handicraft, SMEs

Scale Capital/properties of investment (not

include land) (USD)

Number of employee

(person)

Micro Enterprise < 50,000.00 Less than 10

Small enterprise 50,000.00-250,000.00 10-50

Medium enterprise 250,000.00-500,000.00 51-100

Large enterprise > 500,000.00 >100

Source: Department of SMEs, MIH, 2014 (presentation in Seminar on Green Industry)

Page | 26

Based on the above classification to cassava dried chips, dried starch, wet starch and semi-final product

of cassava known as Sagu and Saray, results from this study have clearly shown variation in their

production chains and their associated waste products.

Cassava dried chip processing

Dried chip, sun dried of fresh chopped cassava root, is processed in both provinces. Nevertheless, the

scale of its production in Pailin is relatively larger than in Kampong Cham province. In Pailin, the area

for dried chip production was constructed under big capital investment, whereas in Kampong Cham,

dried chip was produced mainly at family scale and only then directly supply to the local processing

plant or through cassava dealer. Based on the result of this study, it is suggested that for the production

of 463 Kg dried starch, it requires about 1 ton of fresh cassava root.

In both provinces for the production of dried chip, two methods of cassava chopping were observed, i.e

chopping by hand and by machine. Chopping by hand is commonly practiced in small scale processing

plants and can be found in both provinces, Kampong Cham and Pailin. However, chopping by machine

is found in few occasions only in Pailin (Fig.1).

Figure 1 Processing of cassava dried chip and its wastes

Collecting from

farmers

Domestic Processor

(Dry starch processing)

Fresh root of cassava

(1 ton)

Sun drying (7-14 days)

Storage in warehouse

Chopping by

hand

Export

(Thailand)

Chopping by

machine

Dry Chip (463 Kg)

Solid waste: peel,

debris, flour (9.18 Kg)

Odor of Water from

cassava pulp

Odor of Water when

raining

Air pollution (dust)

(Inside processing area)

Use for Fertilizer, as

wood, kept in field

Page | 27

Based on the results of this study, processing of dried chip has produced several forms of wastes.

Dusting commonly happens within the processing floor and creates air pollution which can be harmful

to both workers and the surrounding environment. Solid waste is another form of waste product

produced by dried chip processing. This solid waste can include the peel of cassava roots, root debris

and cassava flour left on the floor after the processing. It is reported that, for 1 ton of fresh root, there is

about 20 Kg of solid waste. Another form of pollution caused by dried chip processing is in the form of

an unpleasant smell that generally vapors after the rain (Table 26).

Table 26 Production of wastes produced at different stage of dried chip processing

Stage of operation Type of waste generated Average amount of waste/Level of

pollution

Peeling and chopping Peel, stem of cassava, and

other debris

20 Kg/Ton of fresh root cassava

Sun drying Smell 10 m (in normal condition)

Liquid waste from

physiological break down

-

Collecting and other

operation

Noise (if using machine) -

Dusty Depending on wind speed

Cassava dried starch processing

Dried starch is one of the main products produced from fresh cassava root. Cassava starch is used in

preparing several delicious foods. The fresh root to dried starch ratio is 1 to 0.25 which means that 1 ton

of fresh roots produces 250 Kg dried starch.

Out of 8 starch processing plants operated in the country, 3 were involved in this study. Among those, 2

are in Kampong Cham and the other one is in Pailin (Table 24). Results of this study have shown, not

only the production capacity of these dried starch factories that are different, they are also equipped with

different technologies and number of employees (Table 27). The TTY which is located in Kampong

Cham is the largest cassava processing plant. They do have the capacity to produce up to 10T dried

starch in one hour and in one day they can produce up to 200T dried starch. The others two, Sun Art in

Kampong Cham and Tay Meng in Pailin are similar in size of production but number of their employee

is big different (Table 27).

Table 27 Scale of processing factories of dried starch product

Name of

factory Location Capacity

Actual

production

Number of Staff

Full time Contract

TTY Kampong Cham 10 t/hour 200 t/day 70 176

Sun Art Kampong Cham (no info) 50 t/day 40 -

Tay Meng Pailin (no info) 45-60 t/day 13 -

Page | 28

As the daily production capacity of these three factories is different and so the technologies they are

applying, there are different types and quantity of wastes produced by any individual factory. The three

visited factories are equipped with different types of drying systems that use different sources of energy.

Heating system in Tay Meng factory used rice husk as energy source for heating, while black oil is used

in Sun Arth factory and, firewood is used in TTY. These heating sources produce different wastes such

as ashes from rice husk and firewood and, oil spillage from black oil. All the heating system produce

smoke, particularly if the source for heating is black oil.

For a normal operation, TTY factory requires a daily minimum of 800 tons fresh cassava roots.

However, its operation is strictly limited as the factory can be functioning for only during the cassava

harvesting season that lasts for three months between December, January and February. This situation

is also true for other factories. Shortage of supply or no supply of fresh cassava roots beyond this period

is the main reason.

The principle of dried starch processing in the three factories is quite similar especially at Sun Art and

Tay Meng factories, where extraction by using water for cleaning and dewatering and, drying by hot air

is used. In TTY, in addition to the principle used by other two factories, the factory has included in the

system a centrifuge device to extract cyanide compound from final product. The three factories however

use different heating device, a device that has a function to supply heat for drying cassava flour. The

heating source of energy used for the heating device is rice husk in Tay Meng, black oil in Sun Arth and

firewood in TTY. Illustration of a general dried starch processing is shown in the Figure 2.

In the process of producing dried starch, a big quantity of fresh roots and big amount of water are used.

Left over parts of the fresh root such as peel, some soil debris and used water for cleaning become both

solid and liquid wastes. These wastes are produced at different processing stages as indicates in Table

28. Despite there are many waste products derived from dried starch processing which can have strong

negative impact to the environment, especially if no proper management has been taken, most

respondents consider unpleasant smell produced by cassava dried starch processing is the major

disturbing waste as it can reach up to 500 meters in diameter. To minimize the problem, the current

practice applied by the processing plant is to pile the solid waste and then cover them with plastic sheet

(Picture 2). At the moment, this practice is likely to be a good innovative approach to halt the smell

from reaching neighboring farming communities, but for a long term solution a more feasible waste

management practice is needed.

Page | 29

Figure 2: Flow diagram of solid and water waste from dried cassava starch processing

Table 28 Types of wastes for dried starch processing

Unit Operation Waste Quantity of processing wastes

TTY Sun Art Tay Meng

Peeling, cleaning, grating Peel, soil

debris

5% of fresh

root

5% of fresh root 55 T in 4-5 days

production

Waste water (*) (no data) (No data)

Grinding, screening Pulp waste - (a) (+)

Filtration/centrifuge waste water (*) (Not data) (No data)

Starch

residue

- (a) (+)

Drying using hot air ash (No data) NA (no data)

Waste water treatment

plant

Smell 30 m 25m 4 m

Note: (*) all wastewater from dried starch processing = 42 m3/T dried starch, (+) solid waste from separation for starch = 85

T in 4-5 days production, (a).solid waste from separation for starch = 600 Kg per fresh roots


(1 ton)

Peeling, Washing

Grating

Grinding and Screening

Filtration/Centrifuge

Drying using hot air

Cyclone and cooling cyclone

Shifter and packaging

Dry cassava starch

Water

Burning of:

-Oil (for Tay Meng)

-Wood (for TTY)

-Rice husk(for Sun Art)

Water

Peel, soil debris

Pulp waste

Starch residue

Waste water

Waste water

Ash water

Page | 30

Picture plate 2 Solid waste is covered with plastic sheet to halt the smells from reaching to nearby

village

Cassava wet starch processing

Wet starch production is mainly for the production of sagu and saray. Due to the limitation of wet starch

processing plant in the country, only one factory of wet starch processing which is located in Sourng

district, Kampong Cham (Tbaung Khmom) province was used in this study. The factory is considered a

small scale processor, with the capacity of producing wet starch of 30 T of fresh root per day. The

operational flow of wet starch processing is shown in the Fig. 3.

Figure 3: Flow diagram of wet starch processing and associated wastes


(1 ton)

Cleaning, grating, washing

Grinding

Filtrating for starch solution

Wet starch (600 kg)

Water

Water

Peel, soil debris

waste(50 Kg)

Waste water-1

Pot-

1

Pot-

1

Pot-

1

Pot-

1 Waste water-2

Pulp waste � sell

Washing and Dewatering of for wet starch

Lin

e-1

Lin

e-2

----

Lin

e-21

Water

Waste water-3

Water treat Pond-2

Water treat Pond-1

Collecting for solid

Remaining pulp

waste � sell

Page | 31

In the process of wet starch production, several forms of wastes are also produced. These include waste

water, solid waste, and oil spillage (Table 29). Due to their strong and unpleasant smells, solid and

water wastes are considered to have a negative impact on the health and daily lives of people in the area.

As the factory is located close to the village, farmers frequently complain about unpleasant smells

coming from the factory, and especially during the transportation of solid waste through the village.

Moreover, the waste water resulting from wet starch processing can have strong impact to the

populations of fishes and other aquacultures in the areas and can substantially decrease their

populations. In addition, in high concentration waste water can also reduce rice yield if not properly

managed. There were cases where the factory waste water leaked or discharged to farmer’s fields that

destroyed their rice crop and all living aquacultures.

Table 29 Types of waste from wet starch processing

Unit Operation Type of waste Amount of waste

Cleaning, grating, washing Peel, soil debris 50 Kg

Wastewater (1)

Grinding -

Filtrating for starch solution Pulp (cannot estimate)

Wastewater (1)

Washing and Dewatering of wet starch

Waste water (1)

Remaining solid waste starch (cannot estimate)

-outside operation using machine

-Machine operation

Dust 10 Kg/ T fresh

water treatment plant Odor 150 m

Note: (1) waste water cannot be estimated by the processor. The total water for using is 18 times pumping from ground water

per day, using 60 cm diameter pipe.

3.2 Impact of cassava processing wastes on environment

It is known that cassava processing produces a big quantity of wastes that can have negative impact to

the environment and human health (Table 30). Through their strong and unpleasant smell these cassava

processing wastes cause a hostile environment for farming communities living nearby. In addition if

they are not properly managed, the aesthetic and beauty of the environment is also substantially affected

(Picture plate 3).

One of the major threats to the environment by starch processing industry is the content of hydrocyanic

acid and the unbroken down cyanogenic glycoside - linamarin and lotaustralin which produces toxic

Page | 32

and acidic effect in their processing wastes (Okunade and Adekalu, 2013). If these products are not

properly treated, they constitute potent toxicant to the soil, soil organisms, water and plants. During the

process of cassava processing (dried chip, dried starch, and wet starch), it resulted particularly in large

volume of wastewater and solid waste. The quality and quantity of this waste vary greatly due to plant

age, varieties, time after harvesting, kind of industrial equipment used in processing and its adjustment

(Oliveira et al., 2001).

Table 30 Types of wastes produced by cassava processing

Type of waste Cassava processing Produce

odor

Potential impact to

human health and

environment

(Scale of 0-3)1)

Dried

chip

Dried

starch

Wet

starch

Sagu

Solid waste

• Peel Yes Yes Yes No Yes 1

• Stem debris Yes Yes Yes No Yes 1

• Soil debris Yes Yes Yes No No 0

• Flour/Flake Yes Yes Yes Yes Yes 2

• Pulp Waste No No Yes No Yes 1

Liquid waste

• Wastewater No Yes Yes No Yes 3

1). Scale: 0: no impact, 3: with strongest negative impact,

Picture plate 3. Esthetic and beauty of the environment is substantially affected by cassava processing

wastes

Cassava processing generates two types of liquid waste, the first one is produced by washing and

peeling of cassava roots that generally contains a large amount of inert material and, the second one is

produced by draining starch sedimentation tank (Table 3.7).

Page | 33

Wastewater from cassava processing is odorous with unpleasant smell. Due to its high microbial

content, it is subject to a relatively rapid breakdown. This wastewater is normally rich in cyanogens

content therefore it causes a general concern of their possible effect on health and the environment.

However, even with such possible harmful effect, this water can be discharged directly by the factory

onto soils and nearby rivers and streams. It is therefore presenting a strong risk for the environment

through reducing quality of the stream and makes its water less suitable for other downstream users.

Polluted water can cause unpleasant odours and flies infested environment and eventually affect the

health of the inhabitants adversely. This study has observed that wastes from cassava processing and

waste disposal into nearby stream/pond have created severe environmental complications like murky

colour of the stream water, unpleasant odour, and fly nuisance.

To evaluate the environmental impact by cassava processing plants, water sources (open well, deep

well, pond or river) located in close proximity to studied cassava processing plants were collected for

laboratory analysis on the concentration of Total Organic Carbon (TOC) and other parameter related to

the quality of wastewater such as Total Dissolved Solids (TDS) and pH. A total of 56 water samples

were collected from water sources nearby cassava processing areas such as dried chip processing, dried

starch processing plant, and sagu production. In addition samples from wastewater pond that can be

discharged to nearby fields were also taken. Additionally for comparison purpose, another 6 water

samples from Mekong River, from tap water and from bottled drinking water were also collected and

analyzed.

Results of water quality analysis in relation to domestic purposes are presented in Table 31. According

to a general recommended standard for domestic uses, pH of the water should be between 6.00 and 9.00,

and the level of TDS should be between 500-2000mg/L. As there is no available standard for Total

Organic Carbon (TOC), the level of TOC in the samples collected from Mekong River and city tape

water which is at the maximum level of 78mg/L is used as a working standard.

Based on results presented in Table 31, it is clearly demonstrated that water samples collected from

water sources near the cassava processing is either slightly acidic or highly alkaline. In Kampong Cham,

the minimum pH of the samples ranges from 5.7 to 8.8, whereas in Pailin, it ranges from 7.20 to 9.50

(Table 31). Reason for a different effect of cassava processing and its waste into the water sources is not

clear. In addition to the pH level, the quality of water in the surrounding areas is also determined by the

level of TDS. The level of TDS is related to the aesthetic behavior of the water therefore higher TDS

represent a poorer look of the water. Result of the analysis has indicated that only water samples from

Kampong Cham has got maximum level higher than the recommended upper threshold for edible use of

2000mg/L. Therefore water in these areas is not recommended to take either for direct drinking or for

cooking. Similarly in Pailin, despite it is lower than in Kampong Cham, the maximum threshold of

Page | 34

TDS is also very high (> 1000mg/L) as compared to this level at the Mekong river (Table 32), therefore

along with its high pH (a maximum up to 9.50), it should be restricted taking this water for any

household consumption especially for cooking or for drinking.

To increase public health the United States of America has funded a program, name the CALFED

Drinking Water quality to reach a challenging goal of an average concentration of TOC of 3mg/L in

their supplied tape water (CALFED). In our situation (see Table 32), the level of TOC concentration in

the city tape water is still significantly high (68 mg/L) as compared to bottled drinking water (19.5

mg/L).

However, this level is so variable and very high for the water collected from water streams at the

cassava processing areas. There is a strong variation between water samples collected for TOC analysis

at different locations in both Kampong Cham and Pailin (Table 31). In both water layers, the surface

water and the bottom layer, the level of TOC is relatively similar. The level of TOC ranges from 19.5 to

156mg/L with an average of 58.5 and standard variation (SD) of 39 mg/L in Pailin, whereas in

Kampong Cham it ranges from 19.5 to 819mg/L (surface) and 799mg/L (Bottom layer) with an average

of 153.56 (surface) and 172.64 mg/L (Bottom layer) and a standard deviation of 270.89 and 277.29

mg/L in the surface and bottom layer, respectively (Table 31). Apparently, water collected from the

cassava processing areas has high concentration of TOC, therefore any direct use of water from those

sources for either drinking and/or for cooking purposes should be restricted.

Table 31 Physico-Chemical parameters of water samples collected at/near cassava processing plants

Pailin Kg. Cham

pH TDS

(mg/L)

TOC

(mg/L)

pH TDS

(mg/L)

TOC

(mg/L)

Surface

Min 7.20 50.00 19.50 6.40 132.00 19.50

Max 9.50 1760.00 156.00 8.80 2600.00 819.00

Mean 8.27 343.67 58.50 7.94 596.00 153.56

SD 0.67 438.57 39.00 0.90 843.55 270.89

Bottom layer

Min 7.20 50.00 19.50 5.70 134.00 19.50

Max 9.30 1720.00 156.00 8.50 2450.00 799.00

Mean 8.17 341.20 58.50 7.23 654.14 172.64

SD 0.65 428.94 40.47 1.11 826.05 277.29

Well/ borehole

Min 7.00 463.00 39.00 4.40 140.00 19.50

Max 7.10 680.00 136.00 6.30 372.00 117.00

Mean 7.03 580.67 84.42 5.46 217.00 58.50

SD 0.05 87.80 31.68 0.75 99.36 41.37

Page | 35

Table 32 Physic-Chemical parameters of bottled drinking water, tape water and water samples from

Chaktomouk River

pH TDS (mg/L) TOC (mg/L)

River (Chaktomouk) 7.20 63 49

Tape water 7.2 77 68

Bottled drinking water 6.7-6.9 20-32 19.5

Standard for Protected public water area 6.00 – 9.00 < 1000 Not available

Standard for water area and sewer 5.00 – 9.00 < 2000 Not available

US Drinking water standard Average 3 mg/L

Nevertheless, other than all these negative impacts that the wastewater from cassava processing can

have on the environment and human health, there are also positive impacts of this wastewater. It is

known that wastewater contains both organic material and a rich source of nitrogen, therefore if

appropriately managed; this wastewater can certainly be utilized as liquid fertilizer for rice production.

Reports from farmers who have their rice field adjacent to the cassava processing plants confirm this

efficacy of cassava wastewater in boosting their rice yield. In addition, due to its high contents of

cellulose, hemi-cellulose and starch, cassava processing wastewater can as well be effectively utilized

for the production of ethanol (Vo et al., unpublished).

The other type of waste that produced by cassava processing plants is solid waste. Cassava solid waste

can be unrecoverable starch, the peel and soil/stem debris. This type of waste can also have a significant

hazard to the environment and human health of those communities living nearby the processing plants.

Nevertheless, as compared to wastewater, the solid waste is less hazardous to the farming communities

other than its strong and unpleasant smell. During the process of its breaking down, the solid waste is

reported to produce strong and unpleasant smell that can attract houseflies which causes nuisance and

health threaten to people in the area. In some occasions this unpleasant odour can reach up to 200-300 m

and provide good ground for a complaint and/or attacked by people who live around the processing

areas.

Annually, cassava processing produces big quantity of solid waste and if this is not managed properly, it

can cause a serious pollution to the environment and human life. Results of this study suggested that for

the dried chip processing, one metric ton of fresh cassava root produces about 20 Kg of solid waste

(Table 26). Therefore based on this calculation and the exporting quantity of dried chip of 1,269,653

tons in 2013 (MAFF, 2014) and, with a conversion ratio of fresh root to dried chip is 0.463Kg,

presumably at least 54,844 tons of solid waste was produced by local cassava dried chip processing

plants in that year. This is quite a big amount of solid waste produced by cassava dry chip which

Page | 36

without appropriate management it can be not only a wasteful resource but also a source of

environmental pollution.

Nonetheless, solid waste of cassava processing can be a good feed for animal and aquaculture

production. Cassava peel can be utilized as a medium for mushroom cultivation or is used to produce

compost, and for the production of ethanol and maltose (Henry and Howeler, 1996). Currently, most of

the cassava solid waste is dried in the sun for 3-7 days, and then sold to the manufacturing of animal

feed at a low price.

3.3 Awareness of cassava processors on waste management and their constraints in adopting new

waste management

Based on results of individual survey with cassava processing managers in both provinces, we could see

that only 56 per cent of all the interviewed personnel are aware of the impacts that cassava processing

wastes can have on the environment and human health (Table 33). Among all processing plants,

awareness of dried chip processing managers is still limited (18 out of 31), while dried starch and wet

starch processors are fully aware of the problems.

Table 33 Awareness of cassava processors on the impacts of cassava wastes

Cassava processing

Total % Dried Chip Dried Starch Wet Starch Sagu Saray

Aware 18 3 1 1 23 56

Do not aware 13 0 0 5 18 44

Total 31 3 1 6 41 100

Apparently, managers of dried and wet starch processors know well about the impacts of their

processing wastes can have on the environment and human health (Table 3. 10), however due to some

reasons, their waste management is still not appropriately developed as it should be. Two main

constraints that they have indicated are the lack of adequate funding for setting appropriate waste

management plant and the lack of information on new developed technologies on waste management.

When asked many processors responded with enthusiasm in building their own processing plant toward

nationally and internationally recognized standard. However, the uncertainty of local cassava market

and the lack of capital investment restrain them from realizing their dream into the reality. It is true as

many of these local cassava processing plants, especially dried chip processing, are of limited capital

investment and less competitive as compared to their counterparts in the neighboring countries. Some

cassava processors mentioned of their suspicion on new technology despite it is workable in the other

Page | 37

countries. For instance, at least in one occasion, using cassava processing waste for biogas was

interested by the processor, but he is still suspicious about the efficacy of the technology in his local

condition and due to this reason, he is therefore reluctant to invest in establishing the system at his

processing plant.

In practice, all the processing plants have already set up their own waste management system which

contains several waste ponds for the collection of wastewater discharged from the factory. It is likely

that this collected wastewater is left for natural disinfection without using any chemical treatment.

Number of ponds, shape and size are so variable depending on the management decision and the

available capital investment of each concern processing plant. It is obvious that most of the cassava

processing plants have tried their best to establish waste management system. However, it appears that

the system does not follow technical specification, therefore it produces strong unpleasant smell for the

nearby villages and, it is prone to be flooded during the rainy season. In such circumstance, wastewater

that is contained in each pond can then be discharged freely into rice fields or other open water sources

in the area. Vigorous crop growth in the nearby rice fields, in such circumstance, is believed to be

affected by the discharged cassava processing wastewater into the field.

It is well accepted that technology to establish waste management system is available in the country, but

unfortunately those developed technologies are more suitable for larger scale rather than for small and

medium cassava processing plants (Picture plate 4). Furthermore to the gap of this technology

availability, there are other barriers exist that hinder the adoption of the newly developed waste

management system in cassava processing. Those include information gap, limited capital investment

and the degree of confidence of the cassava processing managers on new technologies.

Among the largest dried cassava starch processing plants in the country, TTY has put an investment

plan to build wastewater treatment system and biogas recovery system under the carbon-offset

mechanism but their project is likely on hold due to financial constraints.

Picture plate 4. Waste water treatment tank at TTY factory

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CONCLUSION

Cassava production in Cambodia has expanded exponentially for the last ten years to become the second

largest crop production in the country after rice. Majority of cassava farmers have less than 10 hectares

of cultivated land and the production can be found in two ecosystems, on flat and sloppy land. About

half of the cassava growing is found on sloppy land at the north west region of the country including

Pailin. Despite soil erosion is still not a major concern but with change in climate, it can have a strong

impact to sustainable cassava production in the country.

We found no differences in soil nutrients as well as the level of pH, soil humidity and organic matter in

the areas under cultivation of cassava and those areas under the cultivation of other crops and wild

habitats. Despite it is contradicted to the general belief that cassava plantation can uptake excessive

amount of nutrients from the soil and for that reason can lead to soil nutrient depletion and soil erosion,

this finding suggests that cassava has a similar nutrient withdrawal from the soil as compared to the

other crops. The result of this finding is strongly supported by many authors who concluded that cassava

extracts even less nutrients from the soil than most other food crops.

The expansion of cassava production is probably resulted from changing cropping system which is

prioritized by farmers based on market demand and crop productivity output rather than by claiming

new forest land as previously believed. It is suspected that forest had been earlier cleared for

commercial purpose and/or for the production of other crops such as maize before it has been

transferred to cassava. Nevertheless, as forest data is not available or very difficult to be obtained a

conclusive remark about the effect of cassava production on deforestation cannot be drawn. It is

suggested that this subject should be further analysed in order to provide clear picture on the

relationship between cassava expansion and deforestation.

There are three types of cassava processing plant in Cambodia. Those are dried chip, dried starch and

wet starch processing. Cassava processing produces big quantity of solid and liquid wastes that can have

negative impact to the environment and human health. Through their strong and unpleasant smell

wastewater and solid wastes, cause a hostile environment for farming communities living nearby. In

addition, the aesthetic and beauty of the environment is also substantially affected by cassava processing

if they are not properly managed. Unless these wastes are treated properly and well protected from

leaking to the water stream in the areas, the use of water originated from those areas for drinking and/or

cooking should be avoided.

More than 50 per cent of cassava processing managers recognize the problems arising from their

processing wastes and for that reason most of the processing plants have already set up their own waste

management structure. However, it appears that most of the structures do not follow technical

Page | 39

specification, therefore it produces strong unpleasant smell for the nearby villages and, it is prone to be

flooded during the rainy season. In such circumstance, wastewater that is contained in each pond can

then be discharged freely into rice fields or other open water sources in the area.

It is recognized that newly developed waste management technologies are available in the country, but

they are more suitable for larger scale rather than for small and medium cassava processing plants

which are still struggling to keep their business going. Limited access to those new technologies and the

lack of confident on them are considered the main barrier for developing eco-friendly cassava

processing industry in the country.

Page | 40

RECOMMENDATIONS

Mitigation measures to sustain the country cassava production

It is clear from this study that there is a tendency of yield decline in cassava production in both

provinces. Most influential reasons for yield drop include the decline in soil fertility, invasion of pests

and diseases, and the use of poor planting materials. Despite it is still not a major issue in the country

cassava production, the reported incidence of soil erosion is of concern and along with climate change it

can have a great impact to the future production of cassava unless some mitigation measures have been

taken.

Therefore in order to make cassava production in Cambodia sustainable, some adaptation practices can

be considered, those are:

1. Contour Intercropping

Sloping cassava production can be found in most parts of the cassava production in Pailin and in

some part of Kampong Cham. Soil erosion has though been reported in both provinces. If the

upland areas of Kampong Cham and Pailin will get more rains as it is projected, with the effect

of climate change, soil erosion can be a significant threat to the future cassava production in the

country. Unfortunately, despite damage caused by soil nutrient depletion and erosion are noted,

research support on this subject is still at low profile and it is hard to present the evidence of the

damage by any quantitative figures.

To prevent this climate related risk, a contour intercropping practice is recommended. Cassava is

to be planted on established vegetative/cropping contours. Following a row of lemon grass, a

scrub leguminous plant Leucaena is planted in one high density hedge row. These

complementary two plants hedgerows are to provide as a supporting ground to minimize soil

erosion and keep nutrient leaching especially in heavy rains. In addition to protect the soil from

erosion, Leucaena plant which is known as nitrogen fixation plant can enrich

monocropping/unfertilized cassava production soils a free additional source of nitrogen.

Furthermore Leucaena leaves are rich in protein that can be used for animal production, while

lemon grass which is known of its insect propelling effect can also be good for culinary. The

size of the contours varies depending of the sloping pattern, the steeper is the slope the closer is

the contour. To keep the area of cassava plantation from direct contact with rain drop, a fast

growing crop such as pumpkin is to be planted at the same time of cassava planting. Research

however is needed to identify appropriateness of this practice on different degrees of slopes.

This proposed intercropping is a model that can be modified based on sloping and socio-

economic conditions and, market demand for any specific location.

Page | 41

2. Adequate integrated nutrient balance

As earlier reported, concern about yield decline due to soil fertility depletion is relatively strong

and therefore mitigation measure (s) to convert cassava production back to a more sustainable

system is needed. Application of balanced nutrients, type and quantity, required by the crop can

definitely enhance the growth of cassava especially at the early stage. It is well known that due

to its slowness in growth at the early stage, the areas cultivated to cassava remain open for a

certain period after planting. It is a very critical situation that can lead to large scale soil erosion,

therefore enhancing growth at the early stage is quite important for cassava production. Healthy

plant as a result of proper fertilization can also enhance protective reaction of the crop to the

attacks of pests and diseases. Integrated nutrient management by using combination of fertilizers

including chemical fertilizers, organic manure or compost is also advisable for a sustainable

cassava production in Cambodia.

Even though it is seen as an important measure to alleviate the problem, no fertilizer rate for

cassava has been recommended by any research institution in Cambodia including CARDI. Yet,

result from one experiment in Kampong Cham conducted by CARDI in 2011/2012 has indicated

that the use of compound fertilizer of 15:15:15 (N:P:K) in the rate of 200 Kg/ha plus 50 kg/ha of

a single potassium fertilizer (KCl) produced the highest yield (23 tons per hectare), while a

combination use of 200 kg/ha of 15:15:15 with 10 tons of cow manure yielded 20 tons per

hectare that was comparable to the previous rate but have the highest starch content (27%)

(CARDI, 2012).

It is recognized that for its early growth cassava requires equal amount of nitrogen (N),

phosphorous (P) and potassium (K), but that changes as the plant ages. Depending on which soil

type cassava is grown, demand for N, P and K vary accordingly. Nevertheless, results of long

term experiments in many cassava growing countries have indicated that the most limiting

nutrient to cassava production is potassium (Howeler, 2014) and the rate of 2:1:2 or 2:1:3 for N,

P and K, respectively, are recommended (FAO, 2013).

The lack of fertilizer recommendation rate for cassava production in the country is clearly

demonstrated the need of technical supports that the national research institutions in Cambodia

such as CARDI to come up with their future research strategies in order to develop all essential

technologies to help sustaining cassava production in the country.

3. Minimum and contour tillage

This practice is particularly recommended for cassava production at sloping areas where are very

likely prone to soil erosion. Instead of plowing in a normal way or along the slop, it is

Page | 42

recommended that plowing should be reduced to none or minimum depending on soil

conditions. Similarly tillage should be conducted as much as possible on contour.

4. Production of clean planting materials

Results from this study have strongly suggested that a rapid boom of cassava production in

Cambodia has brought new threats from pests and diseases that originated in other countries.

The free exchange of planting materials across the border is very likely to bring in the country

infected cassava planting materials. Due to this reason, several important pests and diseases have

emerged and caused severe damage on cassava production in the country. It is evidently shown

earlier where 24 percent of farmers in Kampong Cham have reported of severe damage caused

by pests and diseases on their cassava production (Table 8). It is clear therefore that the use of

healthy planting materials is considered the most effective way in controlling pests and diseases

particularly mealy bug and cassava witches-broom (CWB) in cassava production. Cleaned

planting materials production through different techniques can be employed but it is only

possible if there is a strong collaborative effort between relevant players such as CARDI, GDA,

PDA, RUA, International organizations such as CIAT, and NGOs.

5. Cover crop production system

Cassava has generally a slow initial growth, therefore in the case of heavy rainfall soil erosion

and soil nutrient leaching can be very likely to happen. To prevent this situation, in any

cassava production areas, flat or sloping, the use of cover crop such as pumpkin and/or fast

growing legumes is very effective to mitigate the problem. In addition to preventing soil

erosion, the use of cover crops in cassava production can also be regarded as soil improvement

practice and to help reduce weed infestation.

Page | 43

Sustainable utilization and management of cassava processing wastes

Both cassava processing wastes, solid waste and wastewater, can have strong adverse effect to the

environment and human health, but if properly managed they can be very useful in many ways.

Solid waste

• Solid waste derived from cassava peel can be used as feed in animal and aquaculture production.

This is widely practiced, but does have limitations due to its low digestibility and toxicity of the

peel and, on the availability of supplement protein to the feed. These limitations of solid waste

for animal and aquaculture feed can be overcome through several techniques. One effective way

to increase digestibility and to reduce toxicity of the peel is through fermentation. After the

fermentation cassava peel can be converted into a more digestible substrate and can provide

even to pig and poultry. On the other hand, in order to overcome protein deficiency in animal

feed by using cassava peel, one effective way is to establish fully integrated crop-animal and

aquaculture farming system or Model Farming as it is called by CARDI (2006). Currently, a

common practice applied by many cassava processing plants is to let the produced solid waste be

dried in the sun for 3-7 days before it is sold to animal feed manufactory.

• Other than its use for animal feed, solid waste can also be used as a medium for mushroom

cultivation, to produce compost for other crop production, and also can be used for the

production of ethanol and maltose.

Liquid waste or wastewater

• Ideally waste water should only be used after it has been properly treated. Cassava waste

products can be treated by different ways. One way is to build anaerobic and aerobic lagoons

(ponds) to treat the waste before its disposal. In the condition of anaerobic digestion of cassava

waste, cyanide is released in the form of liquor and then liberated by enzymatic and non-

enzymatic reactions. This system is very effective and environmental sound but requires a large

area of land and large capital investment and therefore is suitable only for the large processing

plant. TTY is likely the only cassava processing plant in the country that has set a challenging

plan to establish this system in their factory, but due to financial constraint the plan is likely to

be on hold at the moment.

In case cassava processing is of small to medium scale, waste water can be treated through

channelling the waste into shallow seepage areas. The areas however should be situated away

from natural water sources.

Page | 44

• Cassava processing wastewater can be effectively utilized as a liquid fertilizer, if it is well

treated. However if the waste is not properly treated and due to its high HCN content that can

have a negative effect on plant growth (Taesopapong and Bhanuprabha, 1987; Bengtsson and

Triet, 1994), the use of waste water for irrigation or as a source of fertilizer should be restricted.

The other problem in using wastewater as a liquid fertilizer is to have an appropriate

concentration of wastewater to be used. There is a need therefore to establish this level through

a research study. Failure to determine this may cause serious damage to the rice plants as high

concentration of dilution can cause a total dead of the crop. Result from a study with duckweed

has indicated that when used as a direct fertilizer for duckweed at a dilution rate greater than

60% (waste in water), all duckweed died, but most of the plant can survive and perform well if

its concentration ranges between 10-20 per cent.

• Other than just using as liquid fertilizer, wastewater can also be used to produce biogas and to

generate electricity. This technology which is well known and has been adopted in many cassava

producing countries is now under construction at TTY and Tay Meng.

Page | 45

REFERENCES

Bell, W. R., Seng Vang, Schoknecht N., Hin Sarith, Vancce, W. and White, P. F., 2007. Kampong

Siem calcareous: A new phase for the Kampong Siem Soil group of the Cambodian Agronomic

Soil Clasification. Cambodian J. Agric.,8 (2), 29-35. Phnom Penh, Cambodia.

CALFED. Drinking Water Quality: Organic Carbon. www.science.calwater.ca.gov/pdf/water quality.

CIAP, 1998. Annual research report for 1997. Cambodia-IRRI-Australia Project, Ministry of

Agriculture, Forestry and Fisheries, Phnom Penh, Cambodia.

CARDI, 2012. Balanced fertilizer application to maintain or improve soil fertility, Factsheets.

Cambodian Agricultural Research and Development Institute, Phnom Penh, Cambodia.

CARDI, 2012. Cassava pests and diseases in Cambodia, Factsheets. Cambodian Agricultural Research

and Development Institute, Phnom Penh, Cambodia.

FAO, 2006. World Reference Base for Soil Resources in 2006. Food and Agriculture Organization of

the United Nations, Rome, Italy. 127p.

FAO, 2013. Save and grow cassava: A guide to sustainable production intensification. Food and

Agriculture Organization of the United Nations, Rome, Italy. 130p.

Howeler, R.H, 1991. Long-term effect of cassava cultivation on soil productivity. Field Crops Research

26:1-18.

Howeler, R.H, 2012. Effect of cassava production on soil fertility and the long-term fertilizer

requireemtn to maintain high yield. The cassava handbook, pp: 411-428.

Howeler, R.H, 2014. Sustainable soil and crop management of cassava: A reference manual. CIAT. Pp:

180.

MAFF, 2005-2013. Annual Report. Ministry of Agriculture, Forestry and Fisheries, Phnom Penh,

Cambodia.

MAFF, 2014. Annual Report. Ministry of Agriculture, Forestry and Fisheries, Phnom Penh, Cambodia.

MOE, 2002. Cambodia’s Initial national Communication. Ministry of Environment, Phnom Penh,

Cambodia. Pp: 57

Okunade, D.A.1, and Adekalu, K.O., 2013. Physico-Chemical Analysis of Contaminated Water

Resources Due to Cassava Wastewater Effluent Disposal. European International Journal of

Science and Technology, Vol. 2 No. 6 July 2013. Pp75-84.

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Oliveira, M.A., Reis, E.M., and Nozaki, J. (2001). Biokenetic parameters investigation for biological

treatment of cassava mill effluents. Water, Air and Soil Pollution 126(3-4), 307-319.

Putthacharoen, S., R.H. Howeler, S. Jantawat and V. Vichukit. 1998. Nutrient uptake and soil erosion

losses in cassava and six other crops in a Psamment in eastern Thailand. Field Crops Research

57:113-126.

Seng Vang, Pheav Sovuthy, Hin Sarith, Nou Chanda and Touch Veasna, 2007. Soil and nutrient

management for rice. In: Men Sarom (Ed.), Rice in Cambodia (in Khmer). Cambodian

Agricultural Research and Development Institute. Phnom penh, Cambodia. Pp 197-227.

Seng, V., Bell, R.W., Hin, S., Schoknecht, N., Vance, W., and White, P.F., 2009. Soil factors affecting

crop suitability for upland crops in Cambodia. Cambodian J. Agric., 9 (1-2), 24-37. Phnom Penh

Cambodia

Seng, V., Bell, R.W., Schoknecht, N., Hin, S., Vance, W., and White, P.F., 2007. Ou Reang Ov: A new

soil group for the Cambodian Agronomic Soil Classification. Cambodian J. Agric., 8, 5–12.

Phnom Penh Cambodia

Surapong Charoenrath1, Anurat Srisura2, Kaival Klakhaeng3 and Watana Watananonta, 2012..

Working together for success in Thailand: a case study of Khut Dook "cassava development

village"Cassava Handbook, A reference manual, CIAT

Vo Thi Hanh, Le Thi Bich Phuong, Tran Thanh Phong, Le Tan Hung, Le Thi Huong, . Using wet

cassava waste for ethanol production, unpublished paper.

White, P.., Oberthur, T., and Sovuthy, P. (Eds), 1997. The soils used for rice production in Cambodia: A

manual for their identification and management. Int. Rice Res. Inst. 77p.

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APPENDICES

Appendix 1 Time delivery

# Activities Time frame

Jan Feb Mar Apr May

I Contracting

1 Review documents

2 Developing Methodology

3 Contract signed

4 Developing questionnaires

II Field Operation

5 Field survey

6 Soil and water sampling

7

Laboratory testing of collected soil and

water samples

III Data Management

8 Data entry

9 Data cleaning and analysis

10 Report

Appendix 2 locations where study was conducted

Province District Commune Village

Kampong Cham

Dambe

Kok Srok Kok Cha

Kok Srok

Tropeang Pring Tropeang Pring

Prolos Chom Bork

Memot

Treak Bong Kov

Prey

Memot Muk Kras

Tropeang Rieng

Tbaung Khmom

Srolop Tropeang Dom

Angkor Chey

Lgneang Lgneang

Smornh

Pailin

Pailin

Bor Yakha Bor Yakha

O Chra

O Tavao Dey Kraham

Sou Sdei

Sala Krao

Steung Kach Oro El

Bos Om

O Andaung O Andaung

O rusey

Page | 48

Appendix 3 Cassava Production Questionnaires

SURVEY INSTRUMENT ENVIRONMENTAL IMPACT ASSESSMENT FOR CASSAVA

CULTIVATION

We, at the Royal University of Agriculture are conducting this survey to determine the impact

that cassava cultivation can cause on the environment. You have been randomly selected to

participate in this survey. Your responses will be kept anonymous and confidential. Your

participation is voluntary and you may elect at any time to discontinue participation in the

survey. Survey results will be used to improve smallholder cassava growers/processors economy

in a sustainable manner.

Do I have your consent to start the survey? YES (If YES, proceed with the survey) NO

A. Household Identification

A01. Enter the 2-digit code for Province, District, Commune, Village and household number:

A02. Code of enumerator:

A03. Date of visit: dd/mm/yyyy)

B. History

1. Do you grow cassava? � Yes � No, If yes

2. When started to grow cassava? � in 2013 � Before 2013, Year______________

3. What did you plant before cassava? � Forest � Rubber � Corn/maize

� Soy bean � Others _______________________________

4. Why decided to change to cassava? Please describe ........................................................

..............................................................................................................................................

…………………………………………………………………………………………….

5. Have you ever stopped planting cassava, if so why ..........................................................

...........................................................................................................................................

............................................................................................................................................

C. Production practices:

6. Variety name:_________________________

7. Times of planting � Dry season � Wet season

8. What is the size of your cassava plantation _________Ha________m2______________

Province istrict Commune illage use

Page | 49

9. Topography � Flat � Slope,

If slope,

� How slope is the field � Very steep (> 450) � Steep (300-450)

� Medium (150 – 30 0) � gentle slope (< 150)

10. How did you plow for planting � By contour � Up to down

o By contour, times of plowing and harrowing � One �Two �Three

o Up to down, times of plowing and harrowing � One �Two �Three

11. How to prepare for planting � Raised bed � No bed

12. How to plant � vertical (90o ) � 45o � Horizontal (180o)

13. Planting space � 1m x 0.5m �1m x 1m � 1.5m x 1.m

� 1.5m x 1.5m �Other_________________________________

14. Have you noticed of yield declines from year to year � Yes � No

If yes, what is (are) the reason (s). Please list down

15. What did you do if you notice the problem. Please list down

16. How much yield you have received for the last five years

Type of product Yield (Kg/unit area_____________)

2013 2012 2011 2010 Before 2010

Fresh root

17. Have you ever used mulching? � Yes � No

If yes, what type of mulching? ____________________________________________

_____________________________________________________________________

18. Have you irrigated cassava crop? � Yes � No

If yes, what is the source of water

� River �Lake � Pond � Open well � deep well � Other ______

19. How many time did you irrigate � Frequent � 1 time � 2 times � 3 times

20. Have you applied fertilizer? � Yes � No , if No go to Q.20

21. What kind of fertilizer? � Organic � Chemical � Both

Page | 50

22. Provide history of using fertilizer for the past five years

Fertilizer Type Time of application

Rate (Kg/unit area)

2013 2012 2011 2010 Before

2010

1 Organic

2

3

4

5

6

23. Have you applied pesticide? � Yes � No

If yes, why………………………………………………………………….

• What kind of pesticide?____________________________________________

• How did you know about this pesticide?_______________________________

• Where did you buy it_______________________________________________

Page | 51

• When did you apply it _____________________________________________

24. Mode of harvesting � Machine � Hand pick � Animal plowing

25. Have you cleaned harvested roots with water � No � Yes

If yes, what is the source of water using for cleaning the roots

� River �Lake � Pond � Open well � deep well � Other ______

26. Where do you clean the roots � At the river/lake/pond/well, � Just at the harvested

field � At the house shed/storage

27. What did you do with the harvested roots

Type Amount (Kg)

2012 2013

Home consumption

Feeding animals

Sale Fresh root

Dried Chip

Starch

Sakou

Others

28. What did you do with the cassava stems

� Just keep in the field � Collect and keep as planting materials for next planting

� Burn in the field � Other, please specify_______________________

D. Production share

29. How big is your agricultural production area? ________________Ha__________m2

30. What other crops you have grown for the last five years?

� Corn/maize �Bean � Rice � Others

31. What constraints you are facing with cassava production. Please list down

32. What contribution that cassava has on your household income

Crops/Items Estimated Contribution (%)

Page | 52

2013 2012 2011 2010 Before 2010

Cassava

Rice

Other crops

Animal husbandry

Aquaculture

E. Future Investment

33. What is your future plan

� Stop growing cassava, why____________________________________________

� Grow more cassava, why______________________________________________

� Not sure, why_______________________________________________________

� Any other reasons ___________________________________________________

F. Personal Information

34. What is your educational background: � Never attended � Primary school � High

school � University

35. Household Head: � Male � Female

36. Married status: � Married � Widow (divorced) � Widow (deceased)

37. Number of dependents :___________________________

Thank you for your time!

Page | 53

Appendix 4 Cassava Processing Questionnaires

SURVEY INSTRUMENT ENVIRONMENTAL IMPACT ASSESSMENT FOR CASSAVA

WASTE MANAGEMENT

We, at the Royal University of Agriculture are conducting this survey to determine the impact

that cassava processing can cause on the environment. You have been randomly selected to

participate in this survey. Your responses will be kept anonymous and confidential. Your

participation is voluntary and you may elect at any time to discontinue participation in the

survey. Survey results will be used to improve smallholder cassava growers/processors economy

in a sustainable manner. The survey will take about 20 minutes.

Do I have your consent to start the survey? YES (If YES, proceed with the survey) NO

G. Household Identification

A01. Enter the 2-digit code for Province, District, Commune, Village and household number:

A02. Code of enumerator:

A03. Code of processing plant

A03. Code of interviewee

A04. Date of visit: dd/mm/yyyy)

1. General Information

1.1. What type of business? 1 = sole proprietorship

2= partnership

3= company

1.2. When did you start operating? -----------------------------

1.3. Number of employees/labor Men......................................

Women..................................

1.4. Production/processing area .....................................Sqm

1.5. Locality of the processing

plant

1. Near river/lake

2. Surrounded by cassava/other crop plantation

3. on the middle of the village/city

4. Other (Specify)…………………………….

1.6. What is the capacity of your …………………..…………….tons

Province DistrictD Commune VillageV HouseHo

Page | 54

factory? of…………………………………..per day

1.7. What is the actual operation? …………………..…………….tons

of…………………………………..per day

1.8. How many tons of end-

products do they produce

from 1 ton of fresh roots (or

inputs)?

Product Quantity (ton)/1 ton of fresh roots

Dried chips

Dry starch

Wet starch

1.9. What are the major cassava

products that you process?

Rank them in decreasing

order of quantity produced

(1=the most important).

1= ………………………………………………………………..

2=………………………………………………………………..

3=………………………………………………………………..

4=………………………………………………………………..

5=………………………………………………………………..

1.10. During what month(s) of the

year is the production of these

cassava products highest?

(enter 1 for highest).

1 = Maximum 2 = Moderate

3 = slight

Produ

ct

name

J F M A M J J A S O N D

1.11. What are your main materials

or inputs for your

processing/operation? (Give

example?)

-

-

-

-

1.12. Where do you buy your

material/input from?

-

-

-

-

2. Waste and wastes management

a) Wastes

2.1. What are the wastes/pollutions

from cassava processing?

□ 1= Waste water

□ 2=Solid waste

□ 3=Odor/smell

□ 4=Smoke

□ 5= Noise

Page | 55

□ 6= Air pollution

□ 7= Waste from engine/machine (oil, lubricant,

debris of equipment…)

□ 9=Other

□ 99= Don’t know

2.2. Among those wastes/pollutions,

what is the main

wastes/pollution from your

cassava processing?

(Use code above)

………………………………………..

2.3. Indicate whether the processing

wastes/pollutions occur in the

processing steps:

(Tick code, check all that apply)

(Note: Figure on row in

processing step are:

1=Peeling

2=Chopping

3=Drying

4=Storage

5= Transportation

9=Other

Wastes/polution Processing Step

1 2 3 4 5 9

□ 1. Waste water

□ 2. Solid waste

□ 3. Odor/smell

□ 4. Smoke

□ 5. Noise

□ 6. Air pollution

□ 7. Waste from

engine/machine (oil,

lubricant, debris of

equipment…)

□ 9. Other: …………

b) Waste Water

2.4. Does your cassava processing

operation produce waste water? □ 1= Yes

□ 2= No [Skip to Q2.5]

2.5. If yes, what processing step that

produce waste water?

1=Peeling

2=Chopping

3=Drying

4=Storage

5= Transportation

9=Other

99= Don’t know

2.6. How much amount of water that

comes from your processing

operation for 1 ton of cassava?

………………………………….Liter/ton

2.7. How dirty/degree of pollution of

the waste water from processing

operation?

(rank from 5 the good quality of

water to 1 the worst of water

quality)

□ 1- Very dirty (Cannot drink by either animal or

human)

□ 2- Dirty (Cannot drink but can use for household

use)

□ 3- Slightly dirty (Can use )

□ 4-Good

□ 5- Very Good quality (Normal

99- Don’t know

Page | 56

2.8. Where the waste water flow

into? □ 1=Water Sources (well, natural pond)

□ 2=Infiltrate into soil (ground water)

□ 3=Run off into growing field

□ 4=Drain into water treatment pond

□ 5= Drain/run off into other

□ 9= Other

□ 99 = Don’t know

2.9. Where and how pollute of the

waste water onto the mentioned

places/area on the right column?


Polluted Target area Degree of pollution

No Low Modera

te

Hi

gh

□ 1. Water Sources

□ 2. Infiltrate into

soil

□ 3. Run off into

growing field

□ 4. Drain into

water treatment

pond

□ 5. Drain/run off

into other

□ 6. Direct effect on

human


animal


crop

□ 9. Other: …………

2.10. Have you ever treated your

waste water before draining it

outside the processing plant?

□ 1= Yes,

□ 2= No [Skip to Q2.12]

2.11. If yes, how? □ 1= ……………….

□ 2= …………………………

□ 3= …………..

□ 9= Other


c) Solid Waste

2.12.Does your cassava processing

operation produce solid waste? □ 1= Yes

□ 2= No [Skip to Q2.21]

2.13.If yes, what type of solid waste

that produced from processing

operation?

□ 1- Cassava peel

□ 2-Soil debris

□ 3-Cassava flour/flake

□ 4-………

Page | 57

□ 5-…………

□ 9-Other……………

□ 99-Don’t know 2.14.If yes, what processing step that

produce solid waste?

1=Peeling

2=Chopping

3=Drying

4=Storage

5= Transportation

9=Other

99= Don’t know

2.15.How much amount of solid waste

that comes from your processing

operation for 1 ton of cassava?

………………………………….Kg/ton

2.16.How dirty/degree of pollution of

the solid waste from processing

operation?



quality)

□ 1- Very dirty

□ 2- Dirty

□ 3- Slightly dirty

□ 4-Good

□ 5- Very Good quality (Normal)

99- Don’t know 2.17.Where the solid wastes flow

into? □ 1=Water Sources (well, natural pond)

□ 2=Infiltrate into soil (ground water)

□ 3=Run off into growing field

□ 4=Drain into water treatment pond

□ 5= Drain/run off into other

□ 9= Other


2.18.Where and how pollute of the

solid waste onto the mentioned

places/area on the right column?


Polluted Target area Degree of pollution

No Low Modera

te

Hi

gh

□ 1. Water Sources

□ 2. Infiltrate into

soil

□ 3. Run off into

growing field

□ 4. Drain into

water treatment

pond

□ 5. Drain/run off

into other


human


animal


Page | 58

crop □ 9. Other: …………

2.19. Have you ever treated your solid

waste before throw it out? □ 1= Yes,

□ 2= No [Skip to Q2.21] 2.20. If yes, how? □ 1= ……………….

□ 2= …………………………

□ 3= …………..

□ 9= Other


a) Odor/smell

2.21.Does your cassava processing

operation produce Odor/smell? □ 1= Yes

□ 2= No [Skip to Q3.1]

2.22.If yes, what processing step that

produce Odor/Smell?

1=Peeling

2=Chopping

3=Drying

4=Storage

5= Transportation

9=Other

99= Don’t know

2.23.How degree/dirty of smell/odor

from processing operation?



quality)

□ 1- Very bad smell

□ 2- Bad smell

□ 3- Slightly bad

□ 4-Not bad

□ 5- Good smell (Normal)

99- Don’t know 2.24.How far of smell/odor from your

processing plant? □ 1=Very far……………………Km

□ 2=Far…………………………….Km

□ 3=Near…………………………...Km

□ 4=Very near…………………….Km

□ 9= Other


2.25. Have you ever treated this

smell/odor? □ 1= Yes,

□ 2= No [Skip to Q3.1] 2.26. If yes, how? □ 1= ……………….

□ 2= …………………………

□ 3= …………..

□ 9= Other


3. Capacity (awareness) and constraint in waste management

3.1. What do you understand by the ……………………………………………………………………………

Page | 59

term of “Waste Management”?

(Read out for him/her if s/he

doesn’t know about)

Definition: Waste Management:

this is the collection, transport,

processing, managing and

monitoring of waste materials

……………………………………………………………………………

……………………………………………………………………………

……………………………………………………………………………

3.2. What is your dream waste

management that you like to

have in your factory

3.3. What constraint (s) that hinder

you of not having that dream

waste management?

…………………………

4. Environmental and social impacts

4.1. Have you noticed any change in

fish population in the area


crop production (rice, fruit

trees..) in surrounding area


bird population in your area

4.4. How regular your workers get

sick and what are the

predominant sicknesses you

have observed

4.5. How you treat sick worker(s) 1. send to hospital

2. let them rest at home

3. do nothing

4. Other (please specify)………………

4.6. Have you ever received

complaint from residents

and/or local authority in the

area? If yes, what about?

5. Personal Information

5.1. Position of the interviewee

5.2. Qualification

5.3. Years of experience in the

company

Thank you for your time!

Page | 60

Appendix 4

Details address of Food and Chemical Services Laboratory

FCS, # 52, St. New Street, Sangkat Tumnup Teuk, Khan Chamcar Morn, Phnom Penh, Cambodia

Tel. 012 531000/088 5531000

Email: [email protected]

Page | 61

Appendix 5

A brief general description of topography, physical and chemical characteristics of the 3 cassava soil

groups

Labansiek: occurs on the sides of hills or mountains where once ancient volcanoes were. It occupies

1% of the rice growing area. The predominant feature of this soil group is a uniform of red color

throughout profile. The surface soil has a crumb structure with high degree of aggregate stability and

usually friable. The soil surface has clayey texture, very sticky and slippery when wet. The subsoil is

clayey, usually has a deeper red color than the topsoil and is usually friable with crumb structure. The

fertility of this soil is moderate, and soil pH is slightly acid, although it may be slightly alkaline in some

cases. The CEC and organic matter levels are moderate to high, and also has potentially deficient in N,

P, K and S (White et al., 1997).

Kampong Siem: occur in low areas of a varied undulating landscape of small hills and rises, or at the

footslopes of larger hills or mountains. It occupies 2% of the rice growing area. The surface soil is very

dark gray or black; even when dry, it remains very dark. The texture is clayey, and the clay being very

plastic and sticky when wet and hard when dries. There is considerable swelling and shrinking in this

soil with large cracks appearing in the surface soil when it dries. The soil surface is usually has granular

structure. The subsoil also has clayey texture and it is usually gray to light gray than the topsoil. This

soil group develops from two different rock material, basaltic and limestone rocks. They are always

present within the profile or sometimes on the soil surface. This soil pH ranges from slightly acid to

slightly alkaline. The CEC and organic level are high, but level of N, P and K are low (White et al.,

1997).

O'Reang Eu: commonly found in the mid to upper slope of the plateau. It occupies 1% of the rice

growing area. Its position in the landscape is above Kampong Siem soil and below the Labansiek soil.

The gravel is a distinctive characteristic of this soil group. The surface soil has clayey or loamy texture,

vary color from dark gray to very dark brown with variable amount of fine gravel. The surface has

massive structure and is generally hard when dry. The subsoil has clayey to loamy texture and there are

some abundant of medium to coarse size gravels. The color can be varying from dark brown to dark red

or reddish brown. The subsoil has blocky structure. The soil pH is generally moderate acid and level of

organic matter and level of N, P, K range from low to moderate (Seng et al., 2007).

Kampong Siem Group O'Riang Group Laban Siek Group

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