This makes them quick to break down. Once cut, clippings wither and shrink and sift down to the ground. There they are decomposed by soil organisms such as bacteria and fungi, which makes nutrients available to the lawn. Grass clippings conserve water. By shading the soil from the sun, less moisture is lost to evaporation.
Leaves are a good source of carbon and can also be mulched on the lawn.
Just be sure that no more than of the grass blade is covered. Close the door to the discharge chute. If there is no door, ask a lawn equipment sales or service dealer about attaching one. Use your regular mower, with a mulching blade. Talk to a sales representative about attachments for your particular mower.