Utilization of Sewage, and Agro-Wastes
Production of Single Cell Protein (SCP) on Sewage
Biogas from Sewage
Mushroom Production on Agro-wastes
Vermicomposting is the phenomenon of compost formation by earthworms. Obviously, earthworms play an important role in the cycling of plant nutrients, turnover of organic matter and maintenance of soil structure.
Fig. 21.8. Life cycle of a vermicomposting earthwarm in cow manure (based on Kausal and Bisht, 1992).
They can consume 10-20 per cent of their own biomass per day. The most important effect of earthworms in agro-ecosystems is the increase in nutrient cycling, particularly nitrogen. They ingest organic matter with a relatively wide C:N ratio and convert it to earthworm tissue with a lower C:N ratio. Thus, they affect the physico-chemical properties of soil. In several countries including India significant work has been done. Scientists at Indian Institute of Sciences (Bangalore) have developed methods for frequent decomposition of coconut coir by using earthworms. Prof. B.R. Kaushal and coworkers at Kumaun University, Nainital have done significant work on earthworms, their food materials, food habit, organic matter turnover and established relationships between food consumption, changes in worm biomass, and casting activity of earthworms (Kaushal et al.,
1994). They have also monitored the feeding and casting activity of Amynthas alexandri
on corn, wheat leaves and mixed grasses in laboratory cultures. Casts were produced on surface and sides of the containers. Food consumption varied from 36 to 69 mg/g live worm/day. Cast production ranged from 4 to 6 mg/ g live worm/day (Kaushal et al.,
1994). Some of the known and potential waste decomposer (such as Drawida nepalensis,
etc.) earthworms may be introduced in such places where they are absent. Kaushal and Bisht (1992) studied growth and cocoon production of D. nepalensis
on urine-free cow and horse manure. D. nepalensis
is slow growing vermicomposting species and also shows parthenogenesis. Its life cycle is given in Fig. 21.8.