Actually what you are seeing on top of the soil, is really throughout it. This year my compost is cooking, so I'm having to use synthetic potting soil for my beds and containers. For containers, the synthetic potting mix tends to be way too heavy and retains too much water. To improve the quality of that soil, I add about 20% perlite. The perlight shows up as little white rocks where it is seen on the surface area. Another name for perlite is sponge rock. Next year, I'll likely use a blend of both perlite and vermiculite to improve the drainage and moisture retention of the soil that is used in containers.
Kilie and S.G., thanks. We are fortunate indeed, as we live in the middle of 130 acres of family property that went to my wife and her sister. For the past many years I've maintained about 2.5 acres around the house. This year, on a whim, decided to stretch that out to 5 acres around the house. Is so nice that the process simply involves moving the boundary fence out to where ever we wish.
Eclectic gardening style, drawing from 45 years of interest and experience. Mostly plant in raised beds and containers primarily using intensive gardening techniques.