Answer: I think you may be thinking of using an organic mulch to help suppress weeds, help maintain soil moisture, help moderate teh soil temperature and also feed the soil as it rots down over time. Many gardeners maintain a layer of several inches of organic mulch year round for those purposes. Materials can be shredded bark, sawdust, grass clippings, compost, old rotted leaves, or even straw. Most people use what they have available at reasonable cost and from a nearby source. (You can mix and match.) Apply it to the soil surface, fluff it occasionally with a rake, and top it up as needed with fresh material.
Unfortunately, slugs may be attracted to rotting mulch and may like to hide under it. To control slugs, try stirring the mulch up in mid spring to disturb them, then try control methods such as hand picking (at night when they are active), trapping with beer or yeast baited traps, or encircling susceptible plants with a ring of diatomaceous earth (DE) which is available from garden centers. Attacking the slugs early in the season can help reduce their numbers later on -- also keep in mind that birds, toads and other critters dine on slugs.
I hope this answers your question!
Q&A Library Searching Tips