This episode explores the physical ways surface coverings affect moisture, temperature and weeds without prescribing one universal method. The story keeps the mechanisms clear and the research grounded for a casual listener. Inside this episode: - How bare soil loses water - Shade and still air - Material changes the energy balance - Rain has to pass the layer - Weeds change the water budget Sources include Oregon State University Extension, mulching woody ornamentals, Oregon State University Extension, and USDA Natural Resources Conservation Service, mulching practice standard. This episode is a researched narrative summary. Historical records may be incomplete, translated differently, or interpreted differently by scholars. We distinguish documented facts, estimates, disputed interpretations, and later stories where material. Corrections are l ...