I've seen a whole bunch of threads on here about people complaining that their organic nutes just aren't cutting it, their plant is showing lots of micronute deficiencies, etc etc.
What people need to understand is that when they grow "organic" it is a process. I'll explain how plants get nutrition from the soil, and then it will become pretty damn obvious why your plants aren't really getting the "love" that they need.
First thing is first, when you just dump a bunch of organic matter into a pot you aren't doing shit. Well actually, more often than not all you're adding is shit, but anyway... The whole way that organics work is a process. Once you have organic matter in an area you will attract tiny little bugs that can eat that matter. After they start chowing down, their predators, more tiny bugs, are attracted to the same area. These predators start to eat away at the bugs and the bugs, either through deification or death, exude nutrition into the soil that plants can eat. Plants CANNOT eat organic matter as it is.
What do we know about bacteria and fungi (the tiny bugs)? That their presence and growth is exponential. What does this mean? It means that you will start with 1-100 little critters eating your stuff, and, after a while, you'll end up with millions. You obviously won't have very much nutrition coming from 1-100 little critters, but you will have a sufficient amount coming from millions-billions. This is why soil recipes call for you to WAIT. Just look at subcool's recipe. He says you ought to wait a month, at that point your soil will be full of nutrition and ready to support some plant life.
How exactly are nutrients absorbed through the rhizosphere? The rhizosphere refers to the area around the roots of a plant. Your roots are covered with hydrogen, a cation, which they exchange for other cations as well as attract anions. This is basic chemistry. Obviously if you just put a bunch of organic matter in your pot then the microbes will not have a chance to exude any cations or anions, thus the roots will have nothing to exchange for their hydrogen. If the clay and humus (sand is too large to carry anions or cations) in your soil has a sufficient amount of nutrition then it will exchange its cations for the hydrogen on the roots. This is how the plant gets it nutrients. The rate at which a plant can absorb nutrition is referred to as its CEC (cation exchange rate). The higher it is, the more nutrition your plant can absorb. However their is a limit to a good thing. You don't want your CEC to get too high because that will make it so your roots cannot get sufficient oxygen and/or water and your soil will also have very poor drainage. Balance is the key to a good soil as it is the key to good growing.
The way salt based nutrients (chemical ferts) give your plant nutrition is by skipping the whole process of microbes exuding food and going straight to the roots. Obviously what is not used by the plant is then left in your soil and acts as a build up that can be used later. Most of the time this salt build up is unwanted though and that's why flushing became common practice. Chemical ferts provide immediate, and most of the time, good results. However, the salt based nutrition coming from your chemical ferts results in the death of your microbes. Your soil will no longer be able to provide nutrition to your plants and you will rely solely on ferts to feed your plant. That's why as time goes on you need to add more and more ferts to your grow. There is nothing wrong with this at all, but if you plan on going the route of chemical ferts, don't waste your time with a soil recipe and "organic nutrition."
When adding nutrients remember that their needs to be a balance. This goes back to the anion and cation discussion. Calcium, potassium, sodium, magnesium, iron, ammonium and hydrogen are cations. While chloride, sulfate, nitrate, and phosphate are anions. Remember that cations hang out in the soil, thus the anions must be repelled (again basic chemistry here). What does this mean? When adding nutrition realize that the anions that are not immediately absorbed will be repelled out of your soil solution. If the soil is in a contained area then they will form a cluster of their own away from your clay and humus. This will call for a flush to get rid of them. This is also why you should be careful what nutrition you buy. I've literally seen 0-50-0 in a hydro store before. I literally asked the worker if he was fucking kidding me with that useless nute and he said though he highly suggests against it, many people buy it because they read that phosphorous makes bigger buds. Though P does help out your flowers, all 0-50-0 will do is cause huge fucking problems. In a balanced recipe all the nutrition will be used and you will not experience nute burn. If you are getting nute burn, rethink about what nutes you are using and find a more balanced recipe.
Hope this helps clear up some confusion. If you would like to read more about the topic of organic gardening and nutrition, Teaming with Microbes is your book. Literally everything I covered here is covered in the first two chapters of that book. There is so much more great info in there, and if you can't afford it, it is available on btjunkie as well as other torrenting sites! Good growing and have a good day!
Edit: Well it looks like you guys enjoyed the info so time to add a little more about nutrition uptake.
Fungi and Bacteria are the two primary "workers" for providing nutrition to your plant. Fungi, though much smaller than bacteria individually, form long sort of "tunnels" from your plant's rhizosphere to nutrition found in nearby soil. Fungi are special in that they can break down "harder" materials and bring nutrition through their tunneling systems. They then either keep the nutrients until they die and then exude the nutrition into back into the soil in a plant or bacterial edible form. As said before, fungi break down hard materials, like bones, phosphorous, copper, zinc, etc. As you can probably now tell, fungi are very important. It is also important to note that the best defense against harmful fungi is beneficial fungi. Beneficial fungi out compete harmful fungi every time.
What are harmful fungi? Harmful fungi cause diseases on your plant. They do this by getting their nutrition off of your plant without exchanging anything for the nutrition. This could cause a wide variety of diseases such as root rot, plant yellowing, and other sad looking signs. That is why when you see a problem with your plant people immediately think "deficiency." And it is true, however, the reason is because there is not enough nutrition in your soil for the beneficial fungi to out compete the harmful fungi. That is why having a balanced, sufficient, amount of nutrition will always result in a good looking plant. If the nutrition is there, beneficial fungi out compete harmful fungi every time.
What exactly do bacteria do then? Well, bacteria don't move very far during their life times and they also do not form tunnels. They also don't really break down hard material, so they provide the service of breaking down the softer materials in soil for your plants. Bacteria also store nutrition that would otherwise be lost in soil due to leeching, so they got that going for them too. Also, as a part of the metabolic system of bacteria, they release CO2, this then gets absorbed by the plant via photosynthesis and process continues. The same info about beneficial and harmful fungi is true about bacteria as well.
The two different types of nitrogen ought to be mentioned to provide some additional understanding of nutrition. Fungi absorb a cation form of nitrogen (ammonium, NH4) while bacteria turn that ammonium into an anion version of nitrogen (nitrate, NO3) b/c of a special bacteria called nitrosomonas. MJ plants prefer NO3 and therefor prefer more bacteria in their soil then tress and shrubs, which prefer NH4. The preferred ratio of bacteria:fungi in most annuals is actually 1:1. It is super convenient that this is true because a balance of bacteria and fungi will keep your ph in the exact middle of the spectrum, 6-7, which turns out is perfect for mj grown in soil! It's almost as if the weed plant evolved this way to adapt to the fungus and bacteria that existed in the soil before its creation.
What should be noted is that fungi and bacteria don't just magically appear, they form as a result of your plant's exudates. That is really important to understand in organic gardening. There is always a balance, and you need to respect that balance. Don't look for quick fixes and miracle solutions in organic gardening, it just won't happen. Be patient and good things will happen. I hope this helps y'all understand some more basics about nutrition.
