Substrates and factors for earthworm’s multiplication
- A range of agricultural
residues, all dry wastes, for eg., sorghum straw and rice straw (after
feeding cattle), dry leaves of crops and trees, pigeonpea (Cajanus cajan)
stalks, groundnut (Arachis hypogaea) husk, soybean residues, vegetable
wastes, weed (Parthenium) plants before flowering, fiber from coconut (Cocos
nucifera) trees and sugarcane (Saccharum officinarum) trash can be
converted into vermicompost.
- Animal manures, dairy and poultry wastes, food industry wastes, municipal solid wastes, biogas sludge and bagasse from sugarcane factories also serve as good raw materials for vermicomposting.
Factors affecting earthworm multiplication
Temperature: The optimum temperature for E.fetida is 25°C and it can tolerate a temperature range (0°C -35°C).
Dendrobaena veneta has a low-temperature optimum and is less tolerant to extreme
temperatures. The optimum temperatures for E.eugeniae and P.excavatus were
around 25°C but they die at temperatures below 9°C and above 30°C.
Moisture content : In
vermicomposting systems, the optimum range of moisture contents for most
species has been reported to be between 50-90%. Eisenia fetida and Eisenia
andrei can survive in moisture ranges between (50-90%), but they grow more
rapidly between (80-90%) organic wastes.
Ammonia and inorganic salts: Earthworms
are very sensitive to ammonia and cannot survive in organic wastes containing
high levels of this cation (e.g., fresh poultry litter). They also die in
wastes with large quantities of inorganic salts.
pH:
Most epigenic earthworms are relatively tolerant to pH
and can tolerate pH levels of 5–9, but when given a choice in the pH gradient,
they move toward the more acid material, with a pH preference of 5.0.
Aeration: Earthworms lack specialized respiratory organs, and
oxygen and carbon dioxide diffuse through their body wall. Thus, earthworms are
very sensitive to anaerobic conditions.