Soil and some simple observations

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SuperCPAg

SuperCPAg

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Soil has five components sand, silt, clay, organic matter and pore space. The pore space is supposed to be half air space and half water. Refer to the universally used soil textural triangle to know what type of soil you are using. Compost, which is what most people are referring to as soil, is just that compost, not soil. To have a proper soil you must build with sand (largest portion), compost, small amounts of silt and clay <3%. Compost decomposes and breaks down into available nutrients. Compost is mineralized by microbes, this process produces heat, so if your soil is too hot, the compost has not mineralized properly.
The compost used, timing, and heat in the mineralization process will determine the fertility available.
Not sure what people mean when referring to ‘living soil’ , perhaps someone can explain? If living soil, are you are referring to microbes?
Another observation, everyone says water to runoff……. Watering to runoff depletes all oxygen out of the soil. Oxygen is the key component in respiration when the plant turns sugars into energy. If you remove all oxygen from the soil several times a week, you’ll stunt the growth, not create ‘lock out”. The plant cannot produce enough energy for growth because it cannot respire properly. Read up on respiration and the Krebs cycle. The negative effect on growth is not lock out, it’s poor respiration.
To move pH in a single watering enough to effect nutrient uptake is unlikely. pH=~log H+. To add enough H+ ions to move pH a full point or more in a single watering and restrict uptake is unlikely, not impossible but highly unlikely.
Thought this might be helpful to some.
 
mysticepipedon

mysticepipedon

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Are you a soil scientist in training? I don't know if I've ever seen anyone bring the textural triangle into a grow forum before.

The textural triangle is great for choosing an outdoor site for growing, but not much use for indoor, since very little mineral matter (aside from what's in worm castings) is used. "Soil," in an indoor grow, is a media with significant cation exchange capacity.

As for watering, yes, the roots need oxygen and the plant will sicken and die without it. You'll find hundreds of examples here of growers overwatering and hurting their plants. The soil mix must be able to drain. That's what constituents like perlite are for. Pore space is 50% full of water and 50% full of air for a fairly short moment, between one watering and the next, and is not constant.
 
SuperCPAg

SuperCPAg

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CEC, Cation Exchange Capacity derives from the negative charge of organic matter and any clay in the mix. Sand has no nutrient holding capacity, but it gives the soil structure to allow for ample drainage. Nutritional value comes from either compost being broken down by microbes or added fertility. I’m pointing out a soil comprised of only organic matter is more likely to be overwatered dueto lack of drainage, adding sand will help mitigate overwatering.
watering to runoff, causing anaerobic respiration is more likely a problem than ‘lock out’.
i dont understand your statement an ‘outdoor soil’ is not much use indoors. How do soil properties change indoors vs outdoors?
 
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