A mulch is a layer of material applied to the surface of an area of soil. Its purpose is any or all of the following: to conserve moisture to improve the fertility and health of the soil to reduce weed growth to enhance the visual appeal of the areaA mulch is usually but not exclusively organic in nature. It may be permanent (e.g. plastic sheeting) or temporary (e.g. bark chips). It may be applied to bare soil, or around existing plants. Mulches of manure or compost will be incorporated naturally into the soil by the activity of worms and other organisms.