Composting and Vermicomposting Questions and Answers

Answer: A

When the C : N ratio is too narrow, nitrogen in the compost is lost as ammonia.

Composting microbes need carbon for energy and nitrogen for protein, in a ratio of roughly 25-35 to 1 at the start. If there is too little carbon for the nitrogen present (a narrow ratio, as in fresh manure or green waste alone), the microbes cannot use all the nitrogen, and the surplus is released as ammonia gas. That causes odour and robs the finished compost of nutrient value.

A wide ratio, too much carbon, is what slows or protracts composting. The other two options describe no recognised effect of the C : N ratio.

Answer: D

The ecofriendly process is conversion into compost, biogas or bioethanol.

Composting, anaerobic digestion to biogas and fermentation to bioethanol turn the biodegradable part of solid waste into useful products: soil conditioner, fuel gas and liquid fuel. They recover resources, reduce the waste sent to landfills and cut methane released from rotting waste in dumps.

Open dumping pollutes soil, water and air and breeds disease. Landfilling takes land and can leak leachate and methane. Incineration reduces volume but releases flue gases, dioxins and ash that need careful control. None of them is the ecofriendly choice the question asks for.

Answer: B

These organisms are important in Vermicomposting.

Eisenia fetida (the red wiggler), Lumbricus rubellus (the red earthworm) and Eudrilus eugeniae (the African nightcrawler) are surface-dwelling earthworms that feed on decaying organic matter and breed quickly. They are the standard species for converting kitchen, farm and market waste into vermicompost, a nutrient-rich organic manure.

Nitrogen fixation is done by bacteria such as Rhizobium and Azotobacter, phosphate solubilisation by bacteria and fungi such as Bacillus and Aspergillus, and insect biocontrol by agents such as Bacillus thuringiensis or parasitoid wasps. Earthworms do none of these.