These
types of lawn mowers are designed to leave behind grass
clippings that are finely shredded, doing away with the need for a
collection bag.
This
is in contrast to traditional garden lawn mowers that don't
have mulching capabilities, these
produce clippings that readily mat together and are bulkier. With a
traditional mower the clippings need to be removed from the lawn (by
bag collection or raking), so that the grass doesn't
suffocate under them.
The grass clippings that a mulching mower leaves
behind essentially act as a lawn fertiliser, just as if you
were to apply compost to the lawn. This makes a mulching lawn mower an
ideal machine for the home gardener, giving a ready source of
fertiliser and eliminating the need to deal with the grass
clippings produced
In short, mulching lawn mowers do away with the compost pile, and
instead compost the lawn directly, meaning less work for you.