Let’s talk dirty. Well, no. Let’s talk some more about dirt.
At the most simple, dirt (the inorganic part of garden soil) is small particles of pulverized rock. Dirt can be white beach sand (quartz or 8limestone), black beach sand (volcanic rocks), river silt (water eroded bits of various kinds of rock), the stuff you find in your yard, or even ground up plastic.
I know that someone is thinking “ground up plastic?” and, yes, it is the size of the inorganic particles that is important. Grind up plastic to pieces of 1 mm or less, add organics, air, nutrients and water, and plants will grow. It is the size of the particles that matters and that is why clay is such a bad host for plants.
Clay is a marvel. Its particles are so tiny that we have to use a symbol to talk about their size; the symbol “μm” or micron. Clay particles are about 2 microns in diameter, or 0.000078 inches in size. They are very, very small. It is their size that makes them pack so tightly and keeps air and water from penetrating, making clay a poor medium for garden soil. And worms? No worm can make a home in clay. This is why I dug the clay out of my garden areas. Clay does, however, retain moisture, so some clay can be useful in dry areas. And that is why I added some clay back into the garden soil.
Dirt, then, is tiny bits of rocks that have been weathered by wind and water over eons (or tiny bits of plastic that have been ground up in minutes) until they were finally suitable for plant life.
This brings us to hydroponics – gardening with no soil at all. Commercial hydroponics farms – usually greenhouses – use up to 90 percent less water than regular farming as water is not seriously lost to evaporation or weed growth. Hydroponic gardeners usually use a solution-only system where nutrient filled water circulates around plant roots or one with a solution and passive system. In the latter, there is a non-porous medium (small rocks, pellets of various types, perlite, etc.) that roots can grip as plants grow. The nutrient solution circulates through that medium.
Unless there is a question about hydroponics in the future, that may be my last word on the subject. I was a little girl when I started doing what my husband calls, “playing in the dirt.” I got messy then, and I really prefer it that way now.