temperature was in the soil. They observed that the abundance of earthworm
decreased from summer to winter when there is a decrease in soil surface
temperature.
19.4.4 Soil Texture
Soil texture has a considerable effect on the feeding and burrowing activities of
earthworms, i.e. soil type and soil texture because of its effects on other soil
properties such as moisture, nutrient and cation exchange capacity (Edwards and
Bohlen 1996; Briones and Schmidt 2017). Soil texture also plays an important role
in the amount of water available in the soil. Soil having high loam content had
greater numbers of earthworms as compared to soil having high clay or sand content
(Edwards and Bohlen 1996; Holmstrup et al. 2011). Some shapeless soil with high
sand content forms a compressed structure which inhibits air and water movement in
the soil and hence affects earthworm species (Zhang et al. 2007; Morris et al. 2010;
Briones and Schmidt 2017). El-Duweini and Ghabbour (1965) also observed less
population of Aporrectodea caliginosa in Egypt as the proportion of gravel and sand
increased in the soil. On the other hand, Nordstrom and Rundgren (1974) observed a
significant positive correlation between soil clay content and earthworm abundance.
Lapied et al. (2009) reported that soil rich in clay content has high organic matter
content, which favours earthworm frequency and abundance in the soil. In contrast
to this, they also observed low organic matter content in sandy soil. It was observed
that large content of clay in soil normally supports high population numbers of an
earthworm because of higher water maintenance by the clay, which is an essential
factor for earthworm survival (Baker et al. 1998; Curry 2004; Briones and Schmidt
2017). Thus earthworm prefers soil having high clay content. On the other hand,
Hendrix et al. (1992) observed a positive correlation between earthworm biomass
and the amount of silt content.
The clay content also keeps the organic matter content unchanged by deposition
of organic matter on the surface of clay, which reduces the decomposition of organic
matter (Rice 2002). Hendrix et al. (1992) also observed a positive correlation
between the silt content in the soil and earthworm abundance. Similarly, Baker
et al. (1992) observed weak positive correlations between clay content in the soil and
earthworm abundance. Coarse sand can be a negative factor either because the
abrasive action of sand grains damages their skin or these soils dry out more easily
(Kanianska et al. 2016). The sandy soils have lower ground water level horizons
which makes an anoxic circumstance for earthworm while the upper horizons dry
out very rapidly as a result of discharge and thus both conditions with sandy soil are
lethal for earthworms (Sankar and Patnaik 2018). Yvan et al. (2012) also reported
that the variables such as soil bulk density or soil texture may influence earthworm
growth and activity. Nordstrom and Rundgren (1974) reported that the abundance of
Aporrectodea rosea in alluvial soil was due to higher clay content.
19 Earthworm Communities and Soil Structural Properties
343
decreased from summer to winter when there is a decrease in soil surface
temperature.
19.4.4 Soil Texture
Soil texture has a considerable effect on the feeding and burrowing activities of
earthworms, i.e. soil type and soil texture because of its effects on other soil
properties such as moisture, nutrient and cation exchange capacity (Edwards and
Bohlen 1996; Briones and Schmidt 2017). Soil texture also plays an important role
in the amount of water available in the soil. Soil having high loam content had
greater numbers of earthworms as compared to soil having high clay or sand content
(Edwards and Bohlen 1996; Holmstrup et al. 2011). Some shapeless soil with high
sand content forms a compressed structure which inhibits air and water movement in
the soil and hence affects earthworm species (Zhang et al. 2007; Morris et al. 2010;
Briones and Schmidt 2017). El-Duweini and Ghabbour (1965) also observed less
population of Aporrectodea caliginosa in Egypt as the proportion of gravel and sand
increased in the soil. On the other hand, Nordstrom and Rundgren (1974) observed a
significant positive correlation between soil clay content and earthworm abundance.
Lapied et al. (2009) reported that soil rich in clay content has high organic matter
content, which favours earthworm frequency and abundance in the soil. In contrast
to this, they also observed low organic matter content in sandy soil. It was observed
that large content of clay in soil normally supports high population numbers of an
earthworm because of higher water maintenance by the clay, which is an essential
factor for earthworm survival (Baker et al. 1998; Curry 2004; Briones and Schmidt
2017). Thus earthworm prefers soil having high clay content. On the other hand,
Hendrix et al. (1992) observed a positive correlation between earthworm biomass
and the amount of silt content.
The clay content also keeps the organic matter content unchanged by deposition
of organic matter on the surface of clay, which reduces the decomposition of organic
matter (Rice 2002). Hendrix et al. (1992) also observed a positive correlation
between the silt content in the soil and earthworm abundance. Similarly, Baker
et al. (1992) observed weak positive correlations between clay content in the soil and
earthworm abundance. Coarse sand can be a negative factor either because the
abrasive action of sand grains damages their skin or these soils dry out more easily
(Kanianska et al. 2016). The sandy soils have lower ground water level horizons
which makes an anoxic circumstance for earthworm while the upper horizons dry
out very rapidly as a result of discharge and thus both conditions with sandy soil are
lethal for earthworms (Sankar and Patnaik 2018). Yvan et al. (2012) also reported
that the variables such as soil bulk density or soil texture may influence earthworm
growth and activity. Nordstrom and Rundgren (1974) reported that the abundance of
Aporrectodea rosea in alluvial soil was due to higher clay content.
19 Earthworm Communities and Soil Structural Properties
343