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.
When returned to the lawn, clippings recycle nutrients in an organic, slow-release form that promotes steady grass growth. Returning clippings reduces the amount of supplemental nitrogen fertilizer required by lawns but does not eliminate it entirely. Mow frequently enough that no more than one-third of the grass blade is removed. When grass is growing rapidly in the spring, this may mean mowing every five days instead of waiting a full week. This is necessary for two reasons.