Compost and Mulch
Good compost is the key to nurturing soil life.
Compost is nothing more than organic material that has been decomposed by soil organisms to a relatively fine texture and has a stable nutrient content. Compost is stable in terms of nutrient content but is active soil organic matter. The effectiveness of compost is only as good as the compost itself. The quality of compost will vary greatly and is dependent on the materials used and on the composting processes used. Like humans, soil life will do better if it has diversity in its diet. The more different materials you use in the compost, the more nutritious the food is for the microbes.
Mulch
The ideal mulch is one that is fine textured so that it assimilates into the soil. Fine pine bark mulch is common and is what I use in my raised beds. Other organic mulches that are suitable include: pine needles, seedless hay, and straw. Basically, any brown organic material with fine to medium texture can make a good mulch. The exception would be mulches that have toxins such as cedar.