Proper lawn care requires regular mowing and produces large quantities of heavy grass clippings. Disposal is inconvenient and expensive and takes up space in landfills. An alternative is to leave clippings on the lawn, which saves labor and promotes a healthy lawn. The idea that clippings left on lawns will cause thatch has been disproven. Thatch is a brown, spongy material consisting of dead grass stems and roots.
Excessive thatch is undesirable because it prevents water and air from penetrating to grass roots.
A healthy population of microorganisms and earthworms in the soil can digest thatch. Grass clippings break down quickly and encourage the beneficial earthworms and microorganisms that maintain healthy grass and healthy soil. See fact sheet 7.202, Lawn Care , for more information on thatch management. Clippings and Nitrogen Fertilization Nitrogen is the fertilizer nutrient most used by turf. Clippings contain nitrogen and other nutrients.