Possible Clues:

• Erosion preventive
• Gardening material -- there's lots round Leatherhead
• Matter protecting soil from drying out
• Gardener's bagful
• Vegetable matter spread to protect roots, etc
• Garden dressing
• Soil-enriching covering
• Gardener's application
• Push hand into a load of manure?
• Decaying leaves, bark or compost spread around a plant