Compost heaps break organic matter down with heat and time. Earthworms do something different: they eat it. As food passes through the worm, it is ground, mixed with gut microbes and enzymes, and coated in a thin film of mucus. What comes out is castings.
A gentler product
Castings are finer and more stable than ordinary compost. The nutrients are held in a form that plant roots can take up steadily, which is why vermicompost feeds plants steadily and not in a sudden surge.
Alive, not just rich
A handful of castings carries a living community of microbes that keep soil healthy. Living soil is where roots and microbes work side by side, and castings add to that community instead of replacing it.
It cannot be rushed
A well-fed bed of worms takes weeks to turn waste into castings, and nothing speeds it up. Indian guidance gives a range: the ICAR centre for the north-eastern hills reports compost ready in 45 to 50 days with the red wiggler, Eisenia fetida, while Tamil Nadu Agricultural University gives 75 to 100 days and Kerala Agricultural University 60 to 75 days with another worm. Feed, temperature and moisture all move the number.
That patience is what makes the soil rich.