mulch

Any material used to cover the top layer of soil to protect, insulate, or decorate it, or to discourage weeds or retain moisture.

An organic mulch is a mulch made of natural substances such as leaves or grass clippings.

An interim report by investigators from the Rail Accident Investigation Branch found extensive evidence of crushed leaf mulch on the railhead at many sites on the approach to Salisbury Tunnel Junction.

To apply mulch.

Mulch your vegetable garden to retain moisture and keep weeds down.

To turn into mulch.

I decided to mulch the grass clippings.