In agriculture and gardening, mulch is a protective cover placed wer the soil, primarüy to modify the effects of local climate. A wide variety of natural and synthetic materials are used. Materials used a s mulches vary and depend on a number of factors. Use takes into consideration avanabilir,’, cost, appearance, the effect it has on the son – including chemical and pH, durabilir,; combustibility, rate of decomposition, how clean is it – some can contain weeds or plant pathogens _ Organic resides: grass clippings, leaves, hay, straw, comfrey, shredded bark, whole bark nuggets, sawdust, shells, wood chips, shredded newspaper, cardboard, wool, but also cow manure, etc. Many of these materials also act as a direct composting system, such as the mulching clippings of a mulching lawm mmver, or other organics applied as sheet compos ting Compost: This should be fully composted material to avoid possible phytotoxicity problems, and the ‘.veed seed must have been eliminated, otherwise the mulch vall actually produce weed cover Rock and Gravel: Can also be used as a mulch. In cooler climates the heat retained by rocks may extend the groväng season. Bark Chips: Various grades are produced from the outer bar* layer of timber trees. Sizes vary fmm chin shredded strands to large course blocks. The finer types and attractive but have a large exposed surface area that leads to quicker decay. Layers t-v.ro or three inches deep are usually used, bark is relatively inert and its decay does not demand soil nitrates _ Mulch is usually applied towards the beginning of the growring season, and may be reapplied as necessary: It serves initially to warm the soil by helping it retain heat. This allmvs early seeding and transplanting of certain crops, and encourages faster growth. As the season progresses, the mulch stabilizes temperature and moisture, and prevents sunlight from supporting germinated weed seed.