When Tilled Into Soil...

When tilled into soil at that point, compost doesn't act at once
like powerful fertilizer and won't immediately contribute to plant
growth until it has decomposed further. But if composting is allowed
to proceed until virtually all of the organic matter has changed
into humus, a great deal of biomass will be reduced to a relatively
tiny remainder of a very valuable substance far more useful than
chemical fertilizer.

For thousands of years gardeners and farmers had few fertilizers
other than animal manure and compost. These were always considered
very valuable substances and a great deal of lore existed about
using them. During the early part of this century, our focus changed
to using chemicals; organic wastes were often considered nuisances
with little value. These days we are rediscovering compost as an
agent of soil improvement and also finding out that we must compost
organic waste materials to recycle them in an ecologically sound
manner.