IJERD – International Journal of Environmental and Rural Development (2012) 3-1

Research article
erdStudy on Suitable Moisture for Pellet Compost Making andMachanical Mixing Technique
SOVATH TIM*
Institute of Environment Rehabilitation and Conservation, Cambodia Branch
E-mail: tsovath@gmail.com

BUNTHAN NGO
Royal University of Agriculture, Phnon Penh, Cambodia

SOPHEA TIM
Royal University of Agriculture, Phnon Penh, Cambodia

HAK YUN
Royal University of Agriculture, Phnon Penh, Cambodia

MACHITO MIHARA
Faculty of Regional Environment Science, Tokyo University of Agriculture, Tokyo, JapanLALITA SIRIWATTANANON
Association of Environmental and Rural Development, Thailand
Received 16 December 2011

Accepted 12 March 2012(*: Corresponding Author)

Abstract Pellet compost contributes to sustainable agriculture systems in Cambodia. It
also inspires Cambodian farmers to use organic fertilizers instead of chemical fertilizers inagricultural practices. According to the sustainable agriculture program for environment
conservation of the Institute of Environment Rehabilitation and Conservation (ERECON),
one topic for study concerns machine and mixing techniques with suitable moisture formaking pellet compost. The purposes of the experiment are to study about the process ofmaking pellet compost with two kinds of machines (diskpelleters and mincing machines),
and to identify appropriate moisture for practical use of each machine. There are someparameters for studying the process of making pellet compost of those machines, such as
potential of each machine, percentage of good pellet compost, length of the granule, andcharacteristics of the granule. In identifying moisture, five treatments and threereplications were selected, each of which was added with different amounts of water: T1=750 ml, T2= 900 ml, T3= 1050 ml, T4= 1200 ml, and T5= 1350 ml into 5.505 kg ofcompost mixture compound with 23.36% of water content, which consists of conventional
compost, termite-mound soil and palm sugar with a ratio of 5:0.5:0.005. As a result, forthe diskpelleter machine experiment, we got the best result for treatment T2 which wasadded with 900 ml of water and had 45.42% of water content. The producing capacity ofthis machine was 139.75 kg/h in dry mass. For mincing machine, treatment T3, added with1050 ml of water and having 48.69% of water content, got the best result, with aproducing capacity of 64.39 kg/h in dry mass. Therefore, 45.42% of water content incompost mixture was the best moisture for making pellet compost with the diskpelletermachine and 48.69% of water content in compost mixture was the best moisture formaking pellet compost with the mincing machine.
Keywords: conventional compost, termite-mound soil, pellet compost, water content.

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INTRODUCTION
Pellet compost making is an activity that contributes to the sustainable agriculture system in all
agricultural countries, especially in developing countries like Cambodia. Currently, soil
degradation has been widespread around the world due to agricultural practices depending on
chemical fertilizer only. Therefore, it should be improved from the viewpoint of soil nutrient
substance. Pellet compost combined with conventional compost, soil, and molasses at the ratio of
10:1:0.01 by adding some amount of water has been used for sustainable agriculture (Mihara, M.
and Akimi, F., 2007). According to Mihara et al., (2005) adding 0.01 unit of molasses withmoisture is suitable for crop growing, but if molasses is added in higher amount, the crop growth isreduced and has a shorter life than when normal fertilizer is applied. The compost pellet size
produced by mincing machine was 0.5 cm in diameter and 1 cm in length with the same ratio
above mentioned (Siriwattananon, L. and Mihara, M., 2008). There are many kinds of plant
residues for making conventional compost such as rice straws, sugar cane leaves, corn trees,
grasses or leaves, bean residues, saw dust, bean trees and animal manure that can be used as rawmaterials (Mihara, M. and Akimi F., 2007). According to CEDAC (2008) there are several
composting materials such as liquid bio-fertilizer, chicken manure, bat manure, palm sugar, hill soil,surface soil, ash, and bean residues at the ratio of 50:50:5:3:100:100:50:5, respectively. Moisturedetermination of compost mixture was very important for Extruder machines and Diskpelletermachines. Moisture of compost mixture has a strong effect on compost cohesion and on the speedof pellet compost process. The suitable moisture for Extruder machine was from 35% to 45% andfrom 25% to 35% for diskpelleter machine (Hara, 2001). Furthermore, conventional compost isvery important for making pellet compost, so we should make sure that it does not contain hardwaste and stones that can damage the machine, thus requiring more spending on machine repair.
Pellet compost is used as an organic fertilizer and its production is expensive because it should be
produced with high quality standards, and nutrient substances (Hara, 2001). Advantages of pellet
compost  include  the    ompost’s  bulk  density,  being  for conventional compost 1.9g/cm3, that is, lessthan soil bulk density which is 2.7g/cm3, so whenever rainfall or surface runoff water occurred,conventional compost could be washed out easily. On the other hand, pellet compost stays in thesoil and prevents soil nutrient erosion, is very effective and it is easy for transporting (Mihara, M.
and Akimi, F., 2009). Pellet compost can be used on any kind of crops that will grow well andproduce high yield. Moreover, it does not have an impact on human health and it is economical,
and so farmers can earn money from selling pellet compost (CEDAC, 2008). Therefore, theobjectives of the research are to study the process of making pellet compost with two kinds ofmachines (diskpelleter and mincing machines), and to identify an appropriate moisture for practical
purposes with each machine.
MATERIALS AND METHODS
The research was carried out at the Royal University of Agriculture and it is focused on two
purposes: the processes of making pellet compost with two kinds of machines, and the suitablemoisture of compost mixture for each machine. The materials for this research are: mixture
machine, two pellet compost machines, oven machine, conventional compost, termite-mound soil,palm sugar and water. According to Hara (2001), the process of making pellet compost has eightsteps, which are: composting, mixture agitator, mechanized sieve, molding machine, dryer,
mechanized packaging in bags, distribution and storage, and this method was used in the presentresearch. Diskpelleter machine and mincing machine were used for making pellet compost
combined with conventional compost, termite-mound soil, and palm sugar in the ratio of
5:0.5:0.005. In order to determine the suitable moisture of compost mixture, 5 treatments weredefined and each treatment contained 5.505kg of compost mixture compound added with 5different levels of water; T1: 750 mm, T2: 900 mm, T3: 1050 mm, T4: 1200 mm, and T5: 1350
mm. Moreover, replications for producing pellet compost of each treatment were completed threetimes, as R1, R2, and R3. Data of experiment were collected, such as moisture of compost mixtureⒸ ISERD

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by selecting sample and putting it in oven machine, potential of each machine by weighing totalcompost pellet product with timing during making, compost pellet length by measuring in metersand good pellet compost by separating good and broken compost pellet. Furthermore, according toChrun Rithy (2009), the water content of compost mixture in dry mass was calculated by the Eq.(1)(Norman, 1987).
Md = Ww / Wd x 100(1)

where, Md is the moisture content, d.b. (%), Ww is the weight of water (g) and Wd is the weight ofdry sample (g).
Several software programs were used to analyze all data, based on objectives of the presentstudy. Those programs were Microsoft Excel and SPSS 15 used to compare the significant
difference of 5% for the treatments by analyzing a variance of one-way ANOVA and LSD.
RESULTS AND DISCUSSION
The pellet compost making processes
The pellet composting process was considered, each stage being done in order and all materials
prepared for pellet composting. There are seven stages of making pellet compost by using
diskpelleter machine and mancing machine, as shown in Fig. 1

Function

Process

Controlling-Producting high-quality ofpellet compost

Getting materials:
Conventional compost,
termite-mount soil, sugarplum, water-All materials are in theratio of 5:0.5:0.005-Mixture of all materials
become a solution

Use of mixer machine-Duration: 10 minutes withmoisture content 45%-48%

Use of Pellet compostmachine-Making compost pellet-Prevention of quality
degradation (Water content
reduced to 20% or less)-Collection of compost pellet
Keeping pellet moisture
stable and easy fortransportation-For supporting human needs-Diskpelleter machine andMinching machine

Drying pellet compost-Drying under the roof for
4 to 7 days

Separating pellet compost-Plastic or wire net with adiameter of 1.5 mm

Packing in bags
Distribution and storage

Fig. 1 Process for making pellet compostⒸ ISERD

98-Using plastic bag-Keeping under the roof

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Fig. 2 Moisture of compost mixture (%)
Firstly, materials for making pellet compost include conventional compost, termite-mound soil,and sugar were mixed at the ratio of 5:0.5:0.005 by adding a suitable water amount. We had tomake sure that the conventional compost and termite-mound were in good condition. Secondly, allmaterials were mixed by mixer machine until it became a fine mixture, for about 10 minutes.
Thirdly, the compost pellet was produced by the diskpelleter machine and the mincing machine. In
this stage, compost mixture with suitable moisture was put into the machines, resulting in the
production of pellet compost. Fourthly, after producing pellet compost, this was dried under theroof around 4 to 7 days so its water content could be reduced to 20% or less, being this a suitablemoisture for storage (Hara, 2001). When drying pellets, some of them were cracked, and so it wasnecessary to separate them by sacking with a plastic net. Then, pellet compost was packed inplastic bags in order to keep stable moisture. Finally, pellet compost was distributed and stored
under a roof or cool place. The results of the moisture of compost mixture (Fig. 2) showed thatwater content of conventional compost (CC) was 25.34%. After being mixed with termite-moundsoil and sugar, the water content of compost mixture (CM) was reduced to 23.36%. The treatment
T1 was to add 750 ml of water on 5.505 kg of compost mixture compound, and its water content
increased to 41.65%. 150 ml of water was added, increasing from one treatment to another: T2, T3,T4, and T5 and water content increased to 45.42%, 48.69%, 52.28%, and 55.49% respectively.
The potential of diskpellet machine for producing pellet compost
According to the results in Fig. 3, the potential of treatments using the diskpelleter machine
decreased while water content increased in T1, T2, T3, T4, and T5. The highest potential of thismachine was T1: 49.96 g/s or 180 kg/h in dry mass, that had a higher significant difference than theother treatments (P<0.05). The lowest potential was T5: 25.01   g/s or 90   kg/h in dry mass. Incontrast, even though the treatment T1 had the highest potential value, the compost pellet was alittle bit dry, and so it was easy to be cracked. Furthermore, the good compost pellet after sacking it
is not different to those of T2 and T3 with a significant difference level of P>0.05 (Fig.4). The
results of the experiment in Fig. 5 show that the length of compost pellet is not significant among
treatments (P>0.05). The longest compost pellet length from diskpelleter machine was in treatment
T5: 11.24 mm and the shortest was in treatment T1: 8.93 mm; these compost pellets were 5 mm indiameter.
A survey was applied to 20 people to evaluate moisture and length of pellet compost for eachtreatment. Scores ranged from one to five, with one being very bad to five being very good. Fig. 6shows that the most popular treatment was T2: 3.65 marks for pellet moisture and 3.7 marks forpellet length. Therefore, the best treatment was T2: 45.42% of moisture and 9.43 mm of compost
pellet length using the diskpelleter machineⒸ ISERD99

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Fig. 3 Potential of diskpelletermachine (g/s)* Significant difference at P<0.05

Fig. 6 Suitable characteristicof compost pellet

Fig. 4 Percentage of goodcompost pellet (%)

Fig. 5 Length of compost
from diskpelletermachine (mm)* P<0.05

Fig. 7 Potential of mincing
machine (g/s)

Fig. 8 Percentage of goodcompost pellets (%)* Significant difference at P<0.05* P<0.05

Fig. 9 Length of compost pellet from Fig. 10 Suitable characteristic of compost
Mincing machine (mm)pellet
The potential of the mincing machine for making pellet compost
According to the results in Fig. 7, the potential of treatments using the mincing machine increased,
when water content increased in T1, T2, T3, T4, and T5. The highest potential of this machine wasin T5: 18.88 g/s or 68 kg/h in dry mass and it was not significantly different to treatments T3 andT4 (P>0.05). The lowest potential was T1: 10.5   g/s or 37.8   kg/h in dry mass. In contrast, eventhough the treatment T5 presented the highest value, the compost pellet was too wet, and so it
stuck together and became a big aggregate. The good compost pellet after being separated had asignificant difference to other treatments with a significant level of P<0.05 (Fig. 8). The results ofthe experiment in. Fig. 9 show that the length of compost pellets was non-significant amongtreatments (P>0.05). The longest compost pellet length was in treatment T1: 17.52 mm and theshortest was in treatment T5: 14.07 mm. Those compost pellets were 5 mm in diameter. A surveyⒸ ISERD

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was applied to 20 people to evaluate moisture and length of compost pellets for each treatment.
Scores ranged from one to five, with one being very bad to five being very good. Fig. 10 showsthat the most popular treatment was T3: 3.2 marks for pellet moisture and 3.5 marks for pellet
length. Therefore, the best treatment was T3: 48.69% of moisture and 17.33 mm of compost pellet
length with the mincing machine.
Discussion
According to Hara (2001), the most suitable moisture of compost mixture was 35% to 45% for theExtruder machine and 25%-35% for the Diskpelleter machine. However, the most suitable moistureof compost mixture in this research was 48.69% of water content for the mincing machine. In
addition, the water content of compost mixture from 45.42% to 52.28% could be applied with thismachine, while 45.42% of water content of compost mixture was the most suitable for making
compost pellet by the diskpelleter machine. Moreover, the water content of compost mixture from41.65% to 48.69% could be applied with this machine, too.
CONCLUSION
Based on the results of this research, it can be concluded that the diskpelleter pellet compost
machine has potential to produce pellet compost from 90 kg to 180 kg per hour, while the mincing
machine can produce from 37 kg to 68 kg per hour. According to the results of LSD analysis andsurvey on 20 people about compost pellet characteristics (moisture and length) the optimal choice
when using the diskpelleter machine is treatment T2 added with 900 ml of water on 5.505 kg ofcompost mixture with 23.36%, being the water content of compost mixture after adding water45.42%. For the mincing machine treatment T3 was the most suitable, which was added with 1050
mm of water on 5.505 kg of compost mixture, and the water content of compost mixture after
adding water was 47.69%.
ACKNOWLEDGEMENTS
The authors would like to express their deepest gratitude to the Faculty of Agricultural Technologyand Management, Royal University of Agriculture, Cambodia for their kindly support, and special
thanks to Institute of Environment Rehabilitation and Conservation (ERECON) Cambodia branch
for research funding.
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Hara, 2001. Fertilizer pellet made from composted livestock manure. Extension Bulletins, An International
Information Center for Farmers in the Asia Pacific Region.
Mihara, M. and Fujimoto, A. 2007. Sustainable agriculture with organic fertilizer. Institute of Environment
Rehabilitation and Conservation, Japan.
Mihara. M., Srimuang, R., Ichimiya, M. and Siriwattananon, L. 2005. Reducing nitrogen component losses insurface runoff by application of pellet compost, Journal of Environmental Information Science, 33(5),21-26.
Mihara, M. and Fujimoto, A. 2009. Sustainable farming practices for environmental conservation, Institute ofEnvironment Rehabilitation and Conservation, Japan.
Norman, T. 1987. Paddy drying manual. Food and Agriculture Organization, 14.
Siriwattananon, L. and Mihara, M. 2008. Efficiency of granular compost in reducing soil and nutrient losses
under various rainfall intensities. Journal of Environment Information Science, 36(5), 39-44.

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