IJERD – International Journal of Environmental and Rural Development (2010) 1–1

Research article
erdEarthworm Distribution under Different Land Use Systemsin Northeast of Thailand - Benefit for Land Resource
Reclamation
CHULEEMAS BOONTHAI IWAI
Faculty of Agriculture, Khon Kaen University, Khon Kaen, Thailand
Email: chulee_b@kku.ac.th

MATIPHUM ARPORN AND SURASAK SERIPONG
Faculty of Agriculture, Khon Kaen University, Khon Kaen, Thailand
Received 21 December 2009

Accepted 5 March 2010

Abstract The aims of this paper were to study the influence of land use system type on
earthworm distribution in Northeast Thailand. The experimental systems were a naturalforest, a eucalyptus plantation and an organic agricultural and a conventional agricultural
farming system. The effects of land use systems and their management on the distribution
and characteristics of the earthworm, Pheretima sp. on related soil properties wereinvestigated in the rainy season (August-September 2008) and the dry season (December2008-February 2009) in Baan None Daung Mun, Tumbon Sa-Ead, Amphur Muang, Khon
Kaen, Northeast Thailand. Earthworm populations varied and there were significant
differences between systems (p<0.05). Numbers were highest in the natural forest
followed by the organic agricultural system, lower in the conventional agricultural system
and lowest in the eucalyptus plantation in the rainy season. The same result was found in
the dry season but the organic agricultural system had a higher number of casts than in thenatural forest. The same trend was found for earthworm cast height and cast width. Theresults showed that the earthworm cast width in the eucalyptus plantation was lowest in
the rainy season but not significantly different in the dry season between land uses. Theseresults suggest that land use type strongly influences the abundance and characteristics ofearthworm casts in the various soil ecosystems. The results of soil analyses showed thatthe biological soil quality, measured as soil respiration, in soil samples from each land use
type were not significantly different (p<0.05) from each other but was highest in theorganic agriculture system and lowest in the eucalyptus plantation. The soil respiration inearthworm’s casts was higher than in soil in the rainy season. The results showed that thesoil properties of earthworm casts were different in each land use system. Particularly, theincrease of % silt and % clay and an associated decrease of % sand was found in theearthworm cast compared with the surrounding soil in every land use system. The results
for soil quality showed that the earthworm casts had higher electrical conductivity (EC),organic matter, cation exchange capacity (CEC), total nitrogen, available phosphorus, andcalcium and magnesium concentrations than found in soil especially the level of available
phosphorus in casts.
Keywords earthworm, land use systems, land resource reclamation

INTRODUCTION
Soils of Northeast Thailand generally have low fertility due to their coarse texture and low organic
matter content. Organic matter plays a useful function in supporting plant growth and sustainabilityof a land-use system. The earthworm as a soil invertebrate plays an important role in cycling
nutrients within the terrestrial ecosystem by decomposing organic matter, nutrient cycling andenergy transformation within the food web. The changes of land use from forest to agriculture
affect the biodiversity of soil invertebrates. Soil degradation is related to a decline in activity and© ISERD37

IJERD – International Journal of Environmental and Rural Development (2010) 1–1

diversity of soil fauna among other aspects. The soil biota including soil microbial biomass and soil
fauna provide a means of regulating the transformation of organically bound nutrients into plantavailable forms through mineralization. Dispersion of agrochemical residues from conventional
agriculture into the environment has attracted a great deal of public interest over the past few
decades. The widespread use and misuse of persistent pesticides has resulted in their occurrence
throughout the biosphere. Contamination of land from indiscriminate use of agrochemicals has
been a significant issue for Thailand. Because earthworms play a significant role in soil functioning
and soil fertility, their ecological and physiological features make them excellent indicators of soil
pollution compared to other terrestrial invertebrates (Bunning, 2003). However, limited study has
been undertaken to monitor the ecological significance of the influence of land use systems on theearthworm distribution in Northeast Thailand. The distribution, chemical and physical properties ofearthworm casts as compared to bulk soil under a range of different land use systems in Northeast
Thailand was studied in this paper.
OBJECTIVE
The objective of this paper was to study the influence of four land use systems on the earthworm
distribution in Northeast Thailand: (i) to investigate the potential of the earthworm as a bioindicator
for the change of land use in Thai soil ecosystems; and (ii) to investigate the chemical and physicalproperties of earthworm casts as compared to bulk soil under a range of different land use systems
as related to the distribution of the earthworm Pheretima sp.
MATERIAL AND METHODSThe experimental systems included in this study were a natural forest, a eucalyptus plantation, anorganic agricultural and a conventional agricultural system. The effects of land use systems andtheir management on the distribution and characteristics of the earthworm, Pheretima sp. on related
soil properties were investigated in the rainy season (August-September 2008) and the dry season(December 2008-February 2009) in Baan None Daung Mun, Tumbon Sa-Ead, Amphur Muang,Khon Kaen, Thailand (Fig. 1).

Fig. 1 Study site in Khon Kaen, Northeast Thailand, ○ natural forest, ▲ eucalyptus
plantation, ★ an organic agricultural and ■ a conventional agricultural system
Soils and earthworms were collected at the four different land use systems during 2008-2009. The
study area was selected from paired farms, with one utilizing organic practices (as an organicagricultural land use) and a second adjacent farm using conventional methods (as a chemicalagricultural land use). Pair-wise comparisons of two study sites were made for the agro-ecosystems
in Northeast Thailand within 50 km of the city of Khon Kaen, 450 km NE from the capital
Bangkok. Natural forests and eucalyptus plantations were also used as comparisons. The four© ISERD38IJERD – International Journal of Environmental and Rural Development (2010) 1–1

different land use systems were chosen because of their similarity with respect to the pedalogicalconditions and soil characteristics except for agrochemicals used, agricultural practices andmanagement systems. Soil samples were collected and analysed for pesticide residues(organochlorine, organophosphate, carbamate and pyrethroid groups) and measurements weretaken of physical and chemical properties of soil and earthworm casts. A survey of earthworm
populations was conducted at each land use management site. The sampling site for eachexperimental system (natural forest, eucalyptus plantation, an organic agricultural and a conventional
agricultural system) included 27, 9, 9, and 9 sampling sites, respectively.
RESULTS
Earthworm populations were significantly different between systems (P<0.05). They were highest
in the natural forest followed by the organic agricultural system and lower in the conventional
agricultural system. The lowest population was in the eucalyptus plantation in the rainy season. Thesame result was found in the dry season but the organic agriculture system had the highest numberof casts compared with the natural forest. The same trend was found with the earthworm castheight and width (Table 1). Earthworm cast width in the rainy season was significantly greater in
the natural forest and organic system compared to the conventional agricural system and theeucalyptus plantation was lowest of all. Earthworm cast width in the dry season was snot
significantly different for land use excepting for the eucalyptus plantation site which wassignificantly lower. These results suggest that land-use types are strong factors for determining theabundance and characteristics of earthworm casts in Thai soil ecosystems.
Table 1 The number, height and width of earthworm cast of Pheretima sp. per square meterin different land use system and agricultural practices
Land usesystem

Natural forest
Organic
agriculturalsystem
Conventional
agricultural
system
Eucalyptus
plantation

Number of earthworm
cast per square meter

Earthworm cast height(cm)Earthworm cast width (cm)Rainyseason

Dry season

Rainyseason

Dry season

Rainyseason

Dry season

20.3±1.5a

16.3±3.9b

11.3±2.0a

10.8±2.6a

3.4±0.5bc

4.6±0.9a

9.4±1.9c

19.6±3.8a

9.4±1.1ab

8.0±1.8b

4.4±0.6ab

5.3±0.3a

3.2±0.3d

2±0.5d7.2±2.4bbc

5.0±1.4cd

4.8±1.1a

5.2±1.0a

3.67±0.6d

2.3±1.2d

4.5±0.4d

4.1±0.2d

2.3±0.3d

2.6±0.5cd

Data are expressed as mean + se (n= 20).Values indicated by different letters are significantly different (p < 0.05)

The results showed that the biological soil quality expressed in terms of soil respiration in thefour land use systems was not significantly different (P<0.05). However, the trend was for highest
soil respiration in the organic agriculture system and lowest in the eucalyptus plantation. The soilrespiration in earthworm casts was higher than in soil in the rainy season. The results showed thatthe soil properties of earthworm casts were different in each land use system. An increase in the %silt and % clay and decrease of % sand was found in earthworm casts compared with surrounding
soil in all land use systems. As for chemical properties, the results showed that the soil in theearthworm cast had higher EC, organic matter, CEC, total nitrogen, available phosphorus, andcalcium and magnesium concentrations than in soil and especially higher levels of available
phosphorus. The characteristics of the soils and earthworm casts were comparable (Table 2 and 3).
© ISERD

39

Table 2 The physical soil properties of soil and earthworm cast in rainy season in different land use systems
Bulk density(g/cm3)

Land use system

Natural forest
Organicsystem

Saturated hydrolic conductivity(cm/h)

Particle density(g/cm3)Porosity(%)

Soil Moisture
(%)

soil

cast

soil

cast

soil

cast

soil

cast

soil

cast

1.40±0.19a

1.39±0.04a

0.33±0.29a

0.47±0.49c

2.54±0.05ab

2.62±0.09ab

45±0.07a

47±0.03a20.61±4.75ab

28.30±4.44a

1.49±0.07a

1.45±0.12a

0.79±0.84a

0.92±0.71bc

2.50±0.08b

2.62±0.07ab

40±0.03a45±0.05a22.84±2.71a

26.96±6.22a

1.49±0.09a

1.36±0.08a

1.62±2.48a

2.66±2.32a

2.54±0.12ab

2.60±0.06ab

41±0.06a

48±0.03a18.64±2.55ab

31.95±4.20a

1.58±0.05a

1.35±0.13a

1.16±0.54a

2.98±2.22a

2.53±0.06ab

2.68 ±0.03a

41±0.01a

47±0.03a12.81±6.30b

23.43±3.43a

agricultural

Conventional
agricultural system
Eucalyptus plantation

Table 3 The chemical soil properties of soil and earthworm cast in rainy season in different land use systems
Land usesystem

pH (1:1)

EC(1:5) dS/m

OM (%)

T-N (%)

Avail.P (ppm)

Exch.K (ppm)

soilcastsoilcast

soilcast

soilcast

soil

cast

soil

cast

5.14±0.75a

5.41±0.62a

0.03±0.01a

0.05±0.00a

1.60±0.21a

2.96±1.05a

0.08±0.01 a

0.15±0.05a

8.38±2.38ab

9.46±3.12b

32.67±5.69a

42.67±4.16a

Organic
agricultural
system

5.00±0.46a

6.16±0.31a

0.04±0.00a

0.06±0.03a

1.07±0.61ab

1.90±1.50a

0.05±0.03ab

0.10±0.07a

24.36±17.97ab

39.42±24.97ab

47.67±26.39a

119.00±25.51a

Conventional
agricultural
system.

5.19±0.35a

5.68±0.54a

0.04±0.02a

0.06±0.03a

1.06±0.44ab

2.63±1.34a

0.05±0.02ab

0.13±0.07a

35.58±26.73a

42.13±22.08a

94.67±87.65a

165.33±135.2a

Eucalyptus
plantation

4.76±0.03a

5.99±0.06a

0.03±0.00a

0.06±0.01a

0.71±0.03b

1.66±0.09a

0.04±0.00b

0.08±0.00a

3.68±0.83b

9.22±0.85b

42.33±3.06a

77.67±4.04a

Natural forest© ISERD

IJERD – International Journal of Environmental and Rural Development (2010) 1–1

CONCLUSION
The earthworm, Pheretima sp., has the potential to be a soil bioindicator that can be used to assess
and monitor land use change, soil pollution, soil health and ecosystem functioning under different
land use systems and management practices. Chemical analysis of contaminated soil can beexpensive and uninformative regarding environmental hazards associated with polluted soil. The
use of biomonitoring to evaluate hazardous agrochemical contaminated sites provides a direct,
inexpensive, and integrated estimate of the impact of the contaminant on the ecosystem. Therefore,
the role of soil biota and biodiversity should be urgently recognized as important tools for
improved knowledge and management practices for soil conservation and sustainable land use inThailand. Sustainable agriculture involves the successful management of agricultural resources tosatisfy human needs while maintaining and enhancing environmental quality and conserving
natural resources for future generations. Improvement in agricultural sustainability will require theoptimal use and management of soil fertility and soil physical properties. Both rely on soil
biological processes and soil biodiversity. This implies that management practices which enhancesoil biological activity and thereby build up long term soil productivity and health are beneficial(FAO, 2004). This study found that earthworms could improve biological, physiological andchemical properties of soil. Moreover, earthworm casts contain valuable nutrients that are very
useful for increasing soil fertility and plant production. Earthworm conservation should beundertaken for beneficial land resource reclamation.
ACKNOWLEDGEMENTS
The authors wish to express their sincere thanks to Khon Kaen University for its financial support andto the Faculty of Agriculture and Department of Land Resources and Environment, KKU for theirgenerous provision of facilities to enable this experiment to be carried out. Many thanks go to thefarmers at the study sites. Special thanks go to the Groundwater Research Center, Research Centre forEnvironmental and Hazardous Substance Management (EHsM), National Center of Excellence forEnvironmental hazardous Waste Management, Development Center for Integrated Water Resource
Management in Northeast Thailand, Khon Kaen University, Thailand, Prof. Dr. Machito MIHARA andAssociation of Environmental and Rural Development (AERD) for very kind support. Also, thanks toProf. Dr. Barry Noller for kind editing.

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