In this article. DMSO, or dimethyl sulfoxide, is a by-product of paper making. It comes from a substance found in wood. DMSO has been used as an industrial solvent since the mid-1800s.MSO is easily absorbed by the skin. It's sometimes used to increase the body's absorption of other medications. DMSO is available without a prescription most often in gel or cream form.
Actual soil fertility is the amount of nutrients and moisture derived from the soil by the plants in a given year.
Rich soil means the soil is high in plant nutrients, and doesn't have anything nasty in it that would be harmful to plants. The link has an explanation and list of plant nutrients. Rich soils are often high in organic matter, which turns the soil dark brown or black.