Why can you grow plants hydroponically but if plants in soil get too much water they get root rot and die?
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Plants’ roots need oxygen, as counterintuitive as that seems.
In soil, there are a lot of tiny gaps that hold air. When you over water a plant those gaps stay filed with water instead of air and the plant drowns
Any hydroponic system includes a way to get oxygen to the roots. Sometimes they leave the roots exposed to the air for a while (ebb and flow), or sometimes they pump air into the water like in an aquarium (deep water culture)
Few years back I was trying hydroponic gardening and the roots started to rot. Turns out that there are certain kinds of bacteria that will cause wet roots to rot, eventually killing the plant. Experts in an online forum suggested I buy a bottle of beneficial bacteria and dose that when I changed the water. They explained that the beneficial bacteria would out-compete the destructive bacteria, and it did solve the problem for me. In a week to two the roots went from a dark gooey mess to clean, white, firm & healthy. I did not alter the amount of aeration I was using.
I had read somewhere that there are water roots and soil roots and the two develop based on what the growth medium is,
I’m surprised to not see the real answer here.
Osmositic pressure.
Plants absorb water from the ground by osmosis. Their roots are the membrane.
With osmosis, water flows from where there’s less stuff disolved in it, to where there’s more stuff disolved.
Plants have salts, sugars, starches, and minerals in their internal juices.
Tap water usually has less stuff disolved, so it easily flows into the plant.
With too much water, the water keeps flowing until the cells pop.
The secret to hydroponics is TDS – Total Disolved Solids.
They add solids – fertilizers, minerals, and salts to the water. This is carefully measured and tailored to the plant.
When the amount of stuff in the water matches that of the plant juice, it doesn’t keep flowing into the plant.
Only if the plant dries out slightly, then some of the hydroponic solution will flow in.
There’s also the kratky method where you don’t refill the water. As the water level falls, the roots that are no longer touching the water will develop into oxygen roots and pull oxygen right out of the air.
Typically the top third of the roots desire, and function best when quite dry. In a hydroponic system the medium contains a lot of air, and often times the top roots get very little water (maybe a mist) and the water they do get is high in oxygen.
Hydroponic grow mediums are able to hold a shitload of oxygen in them. Coco for example is very hard to over water as it still holds so much oxygen even when saturated with water
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