Maintaining a uniform soil temperature by insulating the soil. Mulches keep the soil warmer during cool weather and cooler during warm weather. Minimizing soil erosion and compaction from heavy rains, heavy lawn mowers, heavy people and heavy thoughts. Improving soil structure through the decomposition of organic mulches. This is particularly important in heavy soil types.
Mulches keep clay soil from cracking after rains.
Mulches encourage worm activity and other beneficial life in the soil. Reducing weed problems by preventing weed seed germination. Keeping lawn mowers and string trimmers away from tree trunks and surface roots. Few things will bring a horticulturist to tears faster than to see tree trunk damage due to lawn mower blight. Once a tree is damaged from lawn mowers scrapping the trunk or string trimmers bruising the trunk, little can be done to correct the damage.