19.1 Introduction
The soil is the most important asset to the farmer because all agricultural activities
invariably take place on the soil. Therefore, the protection of the soil against
depletion is a good step towards sustainable management of its biological properties that determine long-term stability and productivity. It is generally believed that
soil organisms benefit soil productivity but not much is known to small-scale
farmers about the organisms that live in the soil and the functioning of the soil
ecosystem. Of the soil organisms, earthworms are among the most important soil
organisms because of their crucial roles in the soil (Ebewore and Ovharhe 2016).
They are most ancient soil dwellers known since the Pre-Cambrian and Ordovician
period, i.e. 650–570 million years ago (Lee 1985; Miller and Harley 1999). An
earthworm is a tube or cylinder shaped with a segmented body found in the phylum
Annelida and class Oligochaeta. The class oligochaetes are further divided into two
groups on the basis of habitat and size: microdrili (which includes small aquatic
worms of terrestrial family Enchytraeidae) and megadrili (which larger terrestrial
worms and their aquatic representatives). The megadrilli group mainly consists of
those earthworm individuals who have large numbers and biomass in the soils of
temperate and tropical regions of the world. Earthworms are omnivorous in nature
and consume dead organic matter present in the soil. Charles Darwin gave the
importance of earthworms to soil fertility. They are also known as ecosystem
engineers for their important role in influencing the physical, chemical and biological properties of the soil (Singh et al. 2016a). Many studies have also supported
the beneficial role of the earthworm to the sustainable function of ecosystems
(Barrios 2007).
In the present study, an attempt has been made to highlight the earthworm
communities and their dependence on soil physico-chemical properties. The main
objective of the present study was to know the benefits of earthworm in the soil and
how the soil properties influence earthworm communities.
19.2 Earthworm Classification on the Basis of Ecology
The earthworm usually prefers to live within the soil. But, some species of earthworms also live above ground habitats, i.e. leaf litter layers, organic material
accumulated at the base of epiphytes and even in the intertidal zone (Lee 1985).
However, overall, the soil is the main habitat of earthworms to live, but depending
on the ecological nature, each earthworm species has its own feeding habits on
different food resources. Hence, earthworms are classified into three different ecological categories depending on the soil horizons in which they are most commonly
found (Table 19.1) (Bouche 1977; Lee 1985).
1. Anecic: Anecic earthworms are large sized with uniform pigmentation at their
anterior and posterior end. They are mostly phytophagus and play an important
334
S. Singh et al.
The soil is the most important asset to the farmer because all agricultural activities
invariably take place on the soil. Therefore, the protection of the soil against
depletion is a good step towards sustainable management of its biological properties that determine long-term stability and productivity. It is generally believed that
soil organisms benefit soil productivity but not much is known to small-scale
farmers about the organisms that live in the soil and the functioning of the soil
ecosystem. Of the soil organisms, earthworms are among the most important soil
organisms because of their crucial roles in the soil (Ebewore and Ovharhe 2016).
They are most ancient soil dwellers known since the Pre-Cambrian and Ordovician
period, i.e. 650–570 million years ago (Lee 1985; Miller and Harley 1999). An
earthworm is a tube or cylinder shaped with a segmented body found in the phylum
Annelida and class Oligochaeta. The class oligochaetes are further divided into two
groups on the basis of habitat and size: microdrili (which includes small aquatic
worms of terrestrial family Enchytraeidae) and megadrili (which larger terrestrial
worms and their aquatic representatives). The megadrilli group mainly consists of
those earthworm individuals who have large numbers and biomass in the soils of
temperate and tropical regions of the world. Earthworms are omnivorous in nature
and consume dead organic matter present in the soil. Charles Darwin gave the
importance of earthworms to soil fertility. They are also known as ecosystem
engineers for their important role in influencing the physical, chemical and biological properties of the soil (Singh et al. 2016a). Many studies have also supported
the beneficial role of the earthworm to the sustainable function of ecosystems
(Barrios 2007).
In the present study, an attempt has been made to highlight the earthworm
communities and their dependence on soil physico-chemical properties. The main
objective of the present study was to know the benefits of earthworm in the soil and
how the soil properties influence earthworm communities.
19.2 Earthworm Classification on the Basis of Ecology
The earthworm usually prefers to live within the soil. But, some species of earthworms also live above ground habitats, i.e. leaf litter layers, organic material
accumulated at the base of epiphytes and even in the intertidal zone (Lee 1985).
However, overall, the soil is the main habitat of earthworms to live, but depending
on the ecological nature, each earthworm species has its own feeding habits on
different food resources. Hence, earthworms are classified into three different ecological categories depending on the soil horizons in which they are most commonly
found (Table 19.1) (Bouche 1977; Lee 1985).
1. Anecic: Anecic earthworms are large sized with uniform pigmentation at their
anterior and posterior end. They are mostly phytophagus and play an important
334
S. Singh et al.