https://en.wikipedia.org/wiki/...
- Macropores are over 75 microns in diameter. These are big enough that water in them does not experience much capillary force, and can drain out freely due to the force of gravity.
Air will enter these pores even when the soil is at “field capacity” and allow rapid diffusion of oxygen, even if plant roots don’t “suck them empty”.
- Mesopores are 30 – 75 microns in diameter. Water in these pores won’t just flow down and out because of gravity, but plant root hairs CAN extract water from them.
These fill with water at field capacity, and then plants extract the water over the next few days or weeks.
I think that water in this size of pore is somewhat mobile, up-down and sideways, in response to capillary and other forces. This is where capillarity and “other forces” are approximately equal. Those articles start to have a lot of math at this point!
- Micropores are 5-30 microns in diameter. Capillary forces LOCK that water in place so it doesn’t flow sideway, up or down, but apparently plant root hairs CAN suck at least some water out of them. This is where the plants and soil capillarity play tug-of-war.
https://en.wikipedia.org/wiki/...
