IJERD – International Journal of Environmental and Rural Development (2019) 10-2

Research article
erd

Effects of Earthworm Megascolicidae Population and Litter
Quantity on Soil Properties in Experimental Containers
TAKANORI KANEKO
Graduate School of Agriculture, Tokyo University of Agriculture, Japan
Email: taka1504kaneko@gmail.com

TOMONORI FUJIKAWA*
Faculty of Regional Environment Science, Tokyo University of Agriculture, Japan
Email: t3fujika@nodai.ac.jp

MACHITO MIHARA
Faculty of Regional Environment Science, Tokyo University of Agriculture, Japan
Received 28 March 2019

Accepted 20 October 2019(*Corresponding Author)

Abstract Earthworms are important soil animals and perform vital functions in the soil thatmake better conditions for ecosystem, especially agriculture. Earthworms are involved indecomposing organic matters and mineralizing nutrients, controlling populations ofpathogens, improving and maintaining soil structure and mixing organic matters in the soil.
In this study, we discussed the effects of earthworm population and litter quantity on soilproperties. Earthworm from the family of Megascolicidae was used in this study which is anative family of earthworm in Japan and accounts for more than 95% of earthworm family
there. Experimental containers were set in the laboratory where earthworm population andlitter quantity were controlled to observe its effect on soil properties. The results showed
that, there was tendency of increasing survival percentage of earthworm. The Pearson
correlation coefficient analysis showed that with increase in earthworm population and litteramount, there was increasing tendency in soil aggregates and available nitrogen content.
The results for available phosphorus content and soil microbes did not show any relation
with earthworm number and litter quantity.
Keywords earthworm, Megascolecidae, soil properties, soil aggregates, soil available
nitrogen

INTRODUCTION
Nitrogen in soil is mainly bound in organic matter (e.g. litter) and the amount of nitrogen available
for plant growth depends on complex interactions between roots, microorganisms and soil animals(Bonkowski et al., 2000). Earthworms play an important role in decomposing plant residue in the
short-term through their intensive interactions (Aira et al., 2008; Gomez-Brandon et al., 2010) withthe microbial communities. There are approximately 3000 to 4000 different species of earthworms
and are distributed according to environment conditions like temperature, soil type, water
availability in soil and organic content.
Earthworms are broadly divided into two families, Lumbricidae and Megascolicidae. Also,
they are divided into three groups according to their ecological behavior and feeds on leaf litter.
Epigiec earthworm, which lives on the surface of soil. Endogeic earthworm, which live in the soil
and feed on the soil. Lastly, anenic earthworm, which makes permanent vertical burrows on the soil.
All of them feed on leaves on the soil surface and they drag the leaves into their burrows (Bouche,1977). There are more than 100 species of earthworms found in Japan and more than 95% ofearthworms are considered to be those from Megascolecidae family. The earthworm can havenotable effects on soil structure where the density of the earthworm is high. According to Brown etal. (2001), earthworms directly affect organic matter behavior by their feeding and casting activity.
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IJERD – International Journal of Environmental and Rural Development (2019) 10-2

Feeding of organic matter by Lumbricidae on organic matter increase in N, P, and K content in soil
surface and mounds of earthworm (Darwin, 1881; Salisbury, 1923; Evans, 1948). Different
earthworm ecological roles have different effects on soil aggregation and nutrient cycling. But
there are few studies on soil properties affected by earthworm population and organic matter
quantity. Also, most studies on relationship between earthworm activities and soil properties havebeen on those from Lumbricidae. The investigation of the change in the effects of Megascolicidaeby the number and soil organic matter content should be needed to estimate the earthworm
contribution on soil properties in Japan. And the size, abundance and activity of earthworm canchange in soil physical and chemical properties.
OBJECTIVE
The objectives of this study were to assess the effects of Megascolicidae population and litter
quantity on soil properties in the experimental containers.
MATERIALS AND METHODS
Sampling of Earthworms, Soil and Litter
Epigeic earthworms from Megascolicidae family (Fig. 1) were collected from depth of 5 cm soil
using hand-sorting method. Epigeic earthworms are characterized with making transient galleries
and are found till 30 cm deep in subsurface soil. The soil used in this experiment was Andosol
which are volcanic soils and covers 47% land in Japan. The soil was passed through 2 mm sieve(Fig. 2). Litter were collected from fallen leaves of oak and cereus trees (Fig. 3). The leaves were
cut up into small pieces and mixed with soil. All the samples were collected from the same field inKanagawa prefecture, Japan.

Fig. 1 Megascolicidae used in Fig. 2 Field where samples were Fig. 3 Litter used in this study
this study
collected(mainly oak and cereus)
Experimental Set-up
The size of experimental containers consisted of plastic box was 30 cm in length, 16 cm in breadth and5 cm in height (horizontal cross-sectional area 1/2100 a) for making similar conditions as the field (Fig.
4). The experiments were conducted for 62 days at room temperature maintained between 10 to 15 ̊C in
the laboratory (Fig. 5).

Fig. 4 Schematic diagram of experimental containersⒸ ISERD126

Fig. 5 Experimental containers
set in laboratory

IJERD – International Journal of Environmental and Rural Development (2019) 10-2

The sieved soil was placed in the containers and litter and earthworms were added. Soil andlitter were mixed thoroughly. The patterns of soil organic matter content were set into three groups
of no added litter of 0% added litter, 5% added litter and 15% added litter. Each group had 5subgroups of 0, 1, 3, 5 and 10 numbers of earthworms. For 0% added litter group, the five
microcosm treatments were named from A1 to A5. Likewise, for 5% added litter group, B1 to B5,for 10% added litter group, C1 to C5, respectively (Table 1). Moisture content for each treatment
was tested by using gravimetric method and maintained at 50-60% with regular checking.
Table 1 Experimental treatment patterns
Litter added (%)

Number of earthworms /box0Treatments
A11A23A35A410A50B11B23B30%

5%

15%

5B410B50C1

1C23C35C410C5

Sampling and Parameters Measured
Soil was sampled on 0, 14, 31 and 62 days from the start of the experiments. Soil was sampledfrom different points from surface of the soil. The samples were mixed thoroughly and analyzed fororganic content using ignition loss method, water stable aggregate using Yoder’s Method. And, pH
was measured using portable pH meter, total available phosphorus using Trough method, total
available nitrogen using UV absorption method and colonies of actinomycetes and fungus wereanalyzed using serial dilution and plate count method, respectively.
Statistical Analysis
Pearson coefficient correlation analysis was performed between 2 mm aggregates, total available
nitrogen, organic carbon, pH, total available phosphorus, and biological properties for results
obtained during the experiment.
RESULTS AND DISCUSSION
Survival Percentage of Earthworms
Table 2 shows the survival percentage of earthworms with different amounts of added litter. The
survival rate under the treatment with no added litter was smaller than others. Treatments where
5% of litter was used, survival rate of earthworms increased slightly compared to treatments
without any litter. Treatments with 15% of litter amount showed the highest percentage of survival
rate compared to 0% and 5% litter amount treatments. Survival rate of earthworm was in order ofⒸ ISERD127

IJERD – International Journal of Environmental and Rural Development (2019) 10-20%> 5%> 15% to the litter amount. This result attributes to the fact that, the amount of feeding
material increasing, prolonging the survival rate of earthworms. This tendency that organic matterin the form of litter is the important factor for earthworm survival coincides with that reported in
the Brown et al., (2010) which states that earthworms directly affect matter dynamics by theirfeeding and casting activity.
Table 2 Result of survival percentage of earthworm

A2

Number of earthworms
0 day
1

Number of earthworms
62 days
1A33267

A45480A510550

B2B31312100
67

B45480B510770

C2C3131210067

C45480C510990TreatmentsSurvival (%)
100Relationship Between Various Parameters of Soil Properties
Significant correlations with 99% significance between 2 mm aggregates and mean weight diameter(MWD) in treatment C5 were shown from the result of Pearson correlation coefficient analysisconducted between all the experiment parameters in 15 different treatments (Table 3). Similarcorrelation was also found in other treatments. This result is supported by the result of Kladivko et al.,(1986) which states earthworm activities increases in MWD and stability of aggregates.
No correlation was found between other parameters except for 2 mm and MWD in all treatmentsin the applied conditions. The reason for no correlations can be discussed on the behavior of anecic
earthworm, in experiment duration and scale, which might have limited the activity of earthworms. It
also coincides with results of various researches, such as Lavelle and Martin (2012) which states thatearthworm influence organic matter and nutrient during long term genesis.
Table 3 Result of Pearson correlation coefficient analysis of treatment C5
MWD

>2mm

Organiccarbon

Available
phosphorus

pH

Available
nitrogen

Actinomycetes

MWD

1>2mm

0.9917**

1

Organic carbon

0.76330.72161pH

0.75520.83270.43601

Available
phosphorus-0.2661-0.3864-0.0206-0.83221

Available
nitrogen0.17070.2102-0.5023

0.2745-0.2216

1

Actinomyctes-0.4791-0.52120.2012-0.54240.3600-0.9430

1

Filamentous
fungi-0.5272-0.4192-0.46960.1457-0.6662-0.0801

0.1754Note) Significant difference at **p<0.01Ⓒ ISERD

128

Filamentous
fungi

1

IJERD – International Journal of Environmental and Rural Development (2019) 10-2

Water Resistant Aggregate

100%100%90%90%80%

80%Percentage of aggregates

Percentage of aggregates

Soil aggregates affects porosity, water retention ability, accumulation and decomposition oforganic matter in soil (Ketterings et al., 2002; Winsome and McColl, 1998). According to Decaens(2000), Six et al. (2002), earthworm casts are major source of soil aggregates.

70%
60%

＜0.1 mm50%0.25＞d≧0.1 mm

40%0.5＞d≧0.25 mm

30%

1＞d≧0.5 mm

20%
10%

70%

5%

50%

0.25＞d≧0.1mm
0.5＞d≧0.25mm
1＞d≧0.5mm2＞d≧1 mm30%2＞d≧1 mm

20%

≧2 mm

10%

≧2 mm
0%

15%

A1

Fig. 6 Initial conditions of aggregates at0%, 10% and 15% litter

A2A3A4A5

Fig. 7 Changes in the size of aggregate
from A1 to A5

100%

100%

90%

90%

80%

80%

70%

＜0.1 mm

60%

Percentage of aggregates

Percentage of aggregates＜0.1 mm

40%

0%
0%

60%

70%
60%

＜0.1 mm

50%50%

0.25＞
d≧0.1 mm40%0.5＞
d≧0.25 mm

40%

30%

1＞d≧0.5mm

30%

20%

2＞d≧1 mm20%0.25＞d≧0.1mm
0.5＞d≧0.25mm
1＞d≧0.5mm2＞d≧1 mm

10%

≧2 mm

10%

≧2 mm

0%

0%
B1

B2

B3

B4

C1B5

Fig. 8 Changes in the size of aggregate
from B1 to B5
C1

C2

C3

C4

C2C3

C4C5

Fig. 9 Changes in the size of aggregate
from C1 to C5
C5Day 0Day 62

Fig. 10 Changes in aggregates formationin treatments from C1 to C5

Fig. 11 An aggregate formed during
the experiment (C5)Ⓒ ISERD129

IJERD – International Journal of Environmental and Rural Development (2019) 10-2

It also enhances microbial activity in the soil. The changes in percentage of the aggregation by
the amount of litter shown in Fig. 6 shows the initial aggregate concentration in 0%, 5% and 15%of added litter amount. Water resistant aggregate of 2 mm increase with both the number of theearthworm population and litter amount shown in Fig. 7, Fig. 8 and Fig. 9. Treatments with highest
number of earthworm population and added litter amount had highest percentage of 2 mmaggregates. Treatment C5, with highest earthworm and added litter had 55% of aggregates formed.
From the obtained result, it can be concluded that, litter, a nutrient source for earthworms, greatly
influences the formation of water-resistant aggregates.
Available Nitrogen Concentration

A1

3.6

A2

3.4

A3A4

3.2

A5

3.0

b**

2.8b*a, ba, b

2.6
2.4

a*,**

2.204(mg/100 g)
nitrogen （mg/100
AvaiableNitrogeng）
Available

3.8

3.8
3.6

b*

3.4

b*

3.2

a, ba, b

3.0

B1

2.8

B2

2.6

B3B4

2.4

a*

B5

2.208 12 16 20 24 28 32 36 40 44 48 52 56 60

48 12 16 20 24 28 32 36 40 44 48 52 56 60

Time（days）

Time （days）

Fig. 12 Changes in available nitrogenconcentration of A1 to A5(mg/100 g)
nitrogen（mg/100
AvaiableNitrogeng）
Available(mg/100 g)
nitrogen（mg/100
Avaiableg）
Availableitrogen

Earthworms increase nitrogen content availability for plants (Callaham and Hendrix, 1998) and theactivity of earthworms is important to plant nutrition and nitrogen cycling in the soil. The change inavailable nitrogen by earthworm activity are showed in Fig. 12, Fig. 13 and Fig. 14. The results
showed that increase in the number of earthworm population increased the available nitrogencontent. A tendency of the highest increase in available nitrogen content was seen in treatment withhighest amount of added litter quantity and earthworm population. Earthworms consume large
amounts of plant organic matter that contain considerable quantities of nitrogen, and most of thenitrogen that assimilate into their tissue is released to the soil in the form of excreta. It is concluded
that organic nitrogen changed into available nitrogen with the action of earthworms from theexperiment.

Fig. 13 Changes in available nitrogenconcentration of B1 to B5

3.8

c**

3.6

c*, **

3.4

a,b*, **
a,b*, **
a*, **

3.2
3.0

C1

2.8C2C3

2.6

C4

2.4

C5

2.2048 12 16 20 24 28 32 36 40 44 48 52 56 60

Time （days）

Significant difference at **p<0.01, *p<0.05

Fig. 14 Changes in available nitrogen concentration of C1 to C5Ⓒ ISERD130

IJERD – International Journal of Environmental and Rural Development (2019) 10-2

Lunt and Jacobson (1944), Graff (1971) reported that considerably increase in the amount ofnitrogen in soil surface in the field condition. Nitrogen in soil is mainly bound in the form of litterand is available to plants with complex interaction of roots, soil microbes and soil animals.
Earthworm feeds on litter and release casts which increase amount of available nitrogen. Therefore,
incorporation of litter in the soil where earthworm is present can increase casts or aggregates whichcontains nitrogen. The results also indicate that the more earthworm population and litter, the moreincrease in casts.
CONCLUSION
This study was conducted to clarify the effects of earthworm population and litter quantity on soil
properties by the action of earthworm of Megascolicidae in experimental containers. The results ofthe experiments showed that, with increase in litter amount, survival of earthworms increased.
Similarly, increasing tendency of water-resistant aggregates and available nitrogen was observed.
There was no clear relation found in available phosphorus and microbes in the given conditions. Infuture, to better understand the dynamics of earthworm’s action on soil physical and chemical
properties, analysis of subsurface soil with depth due to Megascolicidae movements should beconducted.
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