Sheep fleece as a mulch is amazing stuff. Adds nitrogen and other nutrients as it breaks down, retains moisture and keeps the soil cool in summer Light coloured wool keeps.the soil cooler than dark. In a greenhouse or polytunnel it stays dry so deters slugs as they don't like crawling on it. A handful in the bottom of a planting hole breaks down fairly fast to release nutrients to the roots. Also makes a good addition to the compost pile as a nitrogen source if you have alot of browns and not enough greens