IJERD – International Journal of Environmental and Rural Development (2014) 5-2

Research article
erd

Effect of Storage Duration in the Quality of Vermicompost
NATTIRA KLEAWKLAHARN
Faculty of Agriculture, Khon Kaen University, Khon Kaen, Thailand

CHULEEMAS BOONTHAI IWAI*
Faculty of Agriculture, Khon Kaen University, Khon Kaen, Thailand
Email: chulee_b@kku.ac.th
Received 12 October 2013

Accepted 11 August 2014(*Corresponding Author)

Abstract A trend of demand for organic products in both domestic and international has
dramatically grown in both rate and expansion. Organic agriculture does not only provide
rich nutrition and toxic free soil but is also have low in production cost. The use ofvermicompost is an alternative way to add organic material in farming and alter the soil
properties in a positive way; for instance, by increasing the soil nutrient availability. To
make use of vermicompost efficiently, it is important to recognize that the quality of thevermicompost may change due to the duration of its storage. This study utilizedvermicompost, which had been maintained for different periods (0, 1 and 3 months) tostudy changes in its biological and chemical qualities. The study found that the amount ofliving bacteria and fungi when storing the vermicompost at a 1 month period and thestorage would remain stable until the third month. The changes in soil chemistry indicatedthat the pH and EC values decreased during storage in the first month from 8.53 to 7.50
and from 1.25 ds/cm to 0.84 ds/cm respectively, and increased again during storage in thethird month, which were 8.33 and 2.18 ds/cm respectively. The changes in amount ofnutrients indicated that nitrogen (TN) and calcium (Ca) were not different throughout thestorage period of three months. On the other hand, the amounts of potassium (TK) andmagnesium (Mg) decreased during storage in the first month and increased in the third
month whereas the amount of phosphorus (TP) increased during the first month of storage
period and stabled in the third month. The changes in both biological and chemicalparameters proved that the vermicompost could be kept up to 3 months with good quality.
Keywords vermicompost, storage, chemical and biological properties

INTRODUCTION
The trend of demand for organic products in both domestic and international agriculture has
increased by a 20 growth rate of percent per year due to the fact that manufacturers and consumers
in turn pay much more attention to hygiene, safety, and environmental pollution (Somkhit, 2006).
Organic agriculture is a farming system that uses the principles of the ecological balance of natural
application to manage agricultural production by incorporating biodiversity of crops, livestock,forestry, fisheries etc. in a supportive and renewable resource in the ecosystem for maximum
benefit and by avoiding using inputs imported from outside the farm. This includes the use ofsynthetic chemical inputs such as fertilizers, pesticides, hormones, antibiotics, etc. In addition,organic agriculture provides high yielding soil, rich nutrient and non-toxic together with low
production cost. Using vermicompost is another alternative input in organic farming. The use ofvermicompost in the planting phase will result in better soil structure and is also efficient withwater and air drainage, greater moisture retention and creates incoherency in soil so that plant roots
can thread and spread widely (Edwards et al., 2011). Vermicompost provides a greater variety ofmicroorganisms than in other normal compost. These microbes act to decompose detritus into
useful organo-nutrients for plant growth. Compost and worm tea have humic acids which containnutrients that are essential to many plants such as phosphorus (P), potassium (K), calcium (Ca),iron (Fe), and copper (Cu) and will be released when needed by plants.
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IJERD – International Journal of Environmental and Rural Development (2014) 5-2

Production of vermicompost is a simple technological process, which uses a mixture oforganic sludge with earthworms to change the composition of the waste and produce the biomodified materials that are useful for crops (Iwai et al, 2013). Vermicompost possesses a moldygrain, fine, brown, and light characteristic material; but its quality inevitably changes with time. In
order to obtain optimum efficiency, it is thus important to know how the quality of vermicompost
may change due to different storage times.
OBJECTIVE
The aim of this study is to follow and understand the change in quality of vermicompost due to theduration of its storageMETHODOLOGY
The study was conducted at the Center for Learning and Development of Earthworms forAgriculture and Environment Faculty of Agriculture Khon Kaen University. To explore the scopeof vermicomposting and sampling vermicompost, the vermicompost produced from Eudrillus
eugeniae worm species commonly called the African Night Crawler were fed a blend of cassava
waste, soil, and cow dung at 7:2:1 ratio. The vermicompost was filled into polypropylene wovenbags which were bound tight. The bags were kept in room at a temperature range of 24◦C to 35◦Cwith no humidity control, for storage periods of 0, 1, and 3 months, for 3 repetitions each before
sampling for analysis of chemical and biological properties. The completed randomize design
experiment is used for analysis of variance of the data (analysis of variance) and analysis of thedifference between the mean by DMRT (Duncan's Multiple Range Test)
Table 1 Chemical properties of individual blend based used in vermicomposting
Properties
pHEC (mS/cm)
Organic Matter (OM %)Total nitrogen (% N)Total phosphorus (% P)Total potassium (% K)

Cassava waste
4.95
0.6778.88
0.24
0.025
0.36

Cow dung
9.20
3.57
54.25
1.35
0.664
0.495

Soil (sandy soil)
5.0
0.35
0.45
0.021
0.008
0.121

Analysis of Chemical Properties
The study of some chemical properties was carried out in the laboratory at the Development andMonitoring Crop and Inputs Group, the Office of Agricultural Research and Development Region 3
Khon Kaen province has analyzed the chemical properties. The pH was measured using a pH meterwith a 1:2 ratio of fertilizer to water, electrical conductivity (EC) by using an electricalconductivity meter, total of nitrogen (total N) by using the Kjeldahl method, total phosphorus (totalP2O5) by using the spectrophotometric molybdovanadophosphate method, total of potassium (totalK2O) by using the flame photometric method and the total calcium (Ca) and magnesium (Mg) byusing atomic absorption spectroscopy.
Analysis of Biological Properties
Fungi: The samples of vermicompost are put into the Erlenmeyer flask with 90 mL of sterile
distilled water before shaking off the microbes and leaving the sediments to settle. Concentration ofthe samples is 10-1. The samples are further diluted with sterile distilled water to obtain 10-2 and 103
concentrations. The diluted soil solution is then taken for a spread plate technique on the rose
Bengal-streptomycin agar supplemented with streptomycin antibiotic of 30 μg/ml concentration.
The dilution is made 3 times with repetitions of each before being fermented at 30 oC for 5-7 days
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IJERD – International Journal of Environmental and Rural Development (2014) 5-2and counting all organisms.
Bacteria: Ten grams of vermicompost samples are put into the Erlenmeyer flask with 90 mL ofsterile distilled water before shaking off the microbes (mixed with sterile distilled water) andleaving the sediments to settle. Dilution of water samples with sterile distilled water is carried out
to obtain 10-3, 10-4, and 10-5 concentrations. The diluted solution is then taken for a pour platetechnique by using the soil extract agar. The dilution is made 3 repetitions each before being
fermented at room temperature for 3 days and counting all microorganisms.
RESULTS AND DISCUSSION
Chemical Quality Changes at Different Storage Periods
The vermicompost has the following retention periods: 0 (new fertilizer), 1 and 3 months. The
results of chemical analysis are shown in Table 2 below.
Acidity and alkalinity (pH): The pH values decreased in the first month and increased in the thirdmonth. The decrease in the first period may be caused by the activities of microorganisms, which
are greater in number and relatively to its increasing population. These activities cause acid tooccur such as via the nitrification process or mechanism for changing potassium into a solubleform. However, again, the increase in the third month is because of higher amounts of calcium andpotassium.
Electrical conductivity (EC): The EC values provided the same analysis results as the pH. The
decreased in the first month from 1.25 to 0.84 and again increasing in the third month period from
0.84 to 2.18 may be due to the amount of increasing microorganisms which was affected to thedecomposition of organic matter results in an increasing of ion causing the EC values to rise.
Total of potash (T-K2O): The total of T-K2O provides a decrease in the first month but increasingin the third month as observed for pH and EC. The increase of EC from 0.63 to 1.13 may be due tothe amount of increasing microorganisms. Some groups of microorganisms may produce microbial
acid which is the proper pH value in primary mechanism for changing potassium into the solubleform (Payal et al, 2005).
Total of phosphorus (T-P2O5): The amount of T-P2O5 increased in the first month from 0.30 to0.66 due to pH value being in the proper range for changing into soluble form. However it
decreased in the third month from 0.66 to 0.30 which is to the same at new fertilizer. The reduction
may be due to the immobilization. Amount of increasing microorganisms in the compost takes
phosphorus in greater quantities for growth.
Total of nitrogen (TN): The TN values slightly increase from 0.33 to 0.47 but not differ
statistically during the study. However increased value indicates that there is nitrogen fixation, aprocess of combining atmospheric nitrogen with other elements to form useful compounds. In
nature, nitrogen is fixed by some microorganisms and by lightning, so the greater number ofmicroorganisms in the third months made TN values rise.
Magnesium (Mg) and calcium (Ca): The amount of magnesium decreased in the first month from
0.27 to 0.22 but increased later in the third month period from 0.22 to 0.31 like Ca slightly
increased in the third month from 0.65 to 0.68. The changing of values is an affected of greaternumber of microorganisms, relate to nutrient release from organic matter (mineralization).
Table 2 Chemical properties of vermicompost at various storage periods
Periods of storage
0 (New fertilizer)
1 month
3 monthes
F-TestCoefficient ofvariation %pH8.53 a
7.50 c8.33 b**EC (ds/cm)
1.25 b
0.84 c2.18 a**TN (%)
0.33
0.43
0.47
ns

T- P2O5 (%)
0.30 b
0.66 a0.30 b
**T- K2O (%)
0.97 b
0.63 c1.13 a**Ca (%)
0.65
0.65
0.68
nsMg (%)
0.27 b
0.22 c0.31 a
**

0.58

4.8

19.86

7.89

6.34

8.17

3.73

Note: Mean (n=3) in the same column followed by the same lower case letters are not significantly different at p≤0.05Ⓒ ISERD118

IJERD – International Journal of Environmental and Rural Development (2014) 5-2

Biological Quality Changes at Different Storage Periods
The results from analysis of biological properties showed that the number of fungi and bacteria has
increased more in the first month of storage. This may be due to microbial activities that are still on
going after fermentation ends. However, when stored for a period of three months, the amounts offungi and bacteria do not differ from the first month. This may be a result of the activity called
extracellular enzyme when storing or fermenting the vermicompost. The first step wascharacterized by a decrease in microbial populations, which resulted in a reduction in the synthesisof new enzymes. The second step was the degradation of the pool of remaining enzymes (Manuelet al, 2007) as shown in Table 3.
Table 3 Biological properties of vermicompost at various storage periods
Periods of Storage
0 (New fertilizer)
1 month
3 monthes
F-TestCoefficient of variation %Number of microorganisms (cfu/g)
Bacteria
Fungi
2.67 x 106 b
2.67 x 102 b
4.00 x 106 a
4.00 x 102 a64.00 x 10 a4.67 x 102 a
**
**
9.38
12.48

Note: Mean (n=3) in the same column followed by the same lower case letters
are not significantly different at p≤0.05

CONCLUSION
The study on the quality change of vermicompost is the study of changes in chemical andbiological properties of vermicompost preserved in different periods (0, 1 and 3 months). It was
found that the chemical properties of the vermicompost are changing differently, and yet there is noclear trend in the changes of pH, EC, total potash and magnesium. Magnesium decreased in thefirst period of storage and increased again in later periods while the total nitrogen and total calcium
were not significantly different throughout the study. For biological properties, it was found thatthe numbers of fungi and bacteria were greater in the new stored compost. However, there is nodifference in the amount when storing at 1 and 3 months. These results showed that microbialactivities had still continued. Therefore, it can be concluded that the fertilizer stored for 3 months isstill in the good quality.
ACKNOWLEDGEMENTS
This research project was funded by The National Research Council of Thailand (NRCT) andNational Science and Technology Development Agency (NSTDA), Integrated Water Resource
Management Research and Development Center in Northeast Thailand, The Research Developingand Learning Centre on Earthworm for Agriculture and Environment and Groundwater ResearchCentre, Khon Kaen University, Thailand. Thanks are extended to the Division of Land Resourceand Environment, Faculty of Agriculture, Khon Kaen University for the support and equipments inlaboratory test. Thank you to Prof. Barry Noller for his kind editing of the manuscript.
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Manuel A., Monroy, F., and Dominguez, J. 2007. Microbial biomass governs enzyme activity decay during
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