**2. Earth worm and its kind**

Among the soil biota, earth worm is one of the major kinds and a key component of tropical and subtropical ecosystems [10, 11]. It helps is soil aggregation, nutrient recycling, litter decomposition, etc. Earthworm improves the soil environment by producing cast, pellets, and galleries. Mucus secretion from the gut of earth worm enhances microbial activity. Around 3000 species of earthworms documented so far [12]. The earthworms are of three types that have been described in **Figure 2**.

The most common earthworms [13] have successfully used in India for vermicompost preparation are:


#### **Table 1.**

*Difference between chemical fertilizer and vermicompost.*

**Figure 3.** *African earthworm (*Eudrilus eugeniae*).*

#### **Figure 4.** *Tiger worm (*Eisenia fetida*).*

#### **Figure 5.** *Asian worms (*Perionyx excavatus*).*


Apart from being ecological engineer, earth worm is a rich source of protein thus it can be used as high quality feed to farm animals. Das et al. [13] reported that earthworm cast increases mushroom production. The brief difference between chemical fertilizer and vermicompost is given in **Table 1**.

Most commonly used earthworm species are: African earthworm (*E. eugeniae*), that is, **Figure** 3, Tiger worm (*E. fetida*), that is, **Figure** 4, and Asian worms (*Perionyx excavatus*), that is, **Figure** 5.
