How do plants extract nutrients from the ground?
permaculture.co.uk
permaculture.co.uk
There is a plethora of home gardeners and/or permaculture resources on the internet that generally like as much organic matter as possible.
I some of that strategy as it's convenient at home to supply nutrients to plants without much work.
But, I can't help but feel it's all sort of wish washy science.
https://www.youtube.com/watch?v=KHZHy3_7PPE
^ I found this guys videos much more satisfactory to "need the facts" mindset. He uses knowledge from the agricultural industry instead of the "organic" approach.
In short, plant roots actually love sand, silt and clay, and actually don't like organic matter around their roots as it causes rot. He suggests that you should always just top feed your plants. (throw compost around the top of the plants only) When people say don't over water your plants, it's not because of the water, but because of the organic matter in your pots mixing with water and making sewerage. (e.g. this is why hydroponics works)
Anyway, I'd suggest watching some of his videos on perfect soil for an opinion you don't find much of in home gardening videos.
(This was touchy for me because when I started gardened everyone described my soil as sandy, shit and told me to amend it with X, Y and Z. I was too lazy to listen at the time and noticed that my plants were perfectly fine growing in sand as long as I top fed regularly.)
Each of those - sand, clay, organic matter have a pore size distribution and different pressure that it releases water at. The amount of water and the pressure that it's released at form what's called a soil matric potential graph. The important thing is balancing those so that the soil moisture is mostly held at a pressure that the roots can access . There is a soil texture pyramid that illustrates the different soil textures and mixtures.
[0] https://www.dpi.nsw.gov.au/content/archive/agriculture-today...
[1] https://topsoilpros.com/what-is-a-soil-texture-chart/
The guy in the video is calling mulch compost. Compost is supposed to be made of green material which contains nitrogen and other nutrients not bark and wood chips. There are different sources of organic matter that contain different nutrients, pore distributions, etc.
I believe he knows what compost is, he is just being lazy about using it interchangeably with what you find at most garden shops. Most commercial bags of garden soil and compost both contain a lot of broken down wood. He is just suggesting you shouldn't really have any organic matter around your roots, except for at the top level. It's good to promote mycorrhizal fungi but only at the top layer etc
I think he mostly ranting about how commercial gardening places just sell "soil" that is mostly always comes with added "compost" e.g. https://shorturl.at/mvwzG
Where as they should sell more clay/silt/sand mixes and encourage top dressing instead.
Most people just fill their pots to the top with those bags and it leads to adverse effects.
I started a company that fractures soil and injects organic matter deep, filling fractures to create drainage and sequester carbon, we use biochar - it has a sandy texture and doesn't break down very quickly because it's been pyrolyzed (anaerobic combustion that produces a charcoal/activated carbon like material that looks like black sand). Integrated pyrolyzed organic matter is how slash/burn ag works in the rainforest and is why Brazil has some soils that are black.
I'm going to try make my own ad hoc terra preta plots for fun too. Are you able to share any more information on your company? Who is actually buying this service?
I feel like biochar is going to hit the main stream this year or next.
Going to make a compost tea and soak my bio char in it too.
> anaerobic combustion that produces a charcoal/activated carbon
I wonder if this is the trick though, not that there is organic matter down there, but that is already broken down and fully activated the charcoal.
It would also be great to know if the beneficial fungal processes happen at those depths. So many questions aha
Some of the organic material breaks down really slowly, providing some nutrients to bacteria at a rate that allows the gas to escape, but yea essentially the trick is the ultra high surface area and high compressive strength so that it maintains a porous structure instead of compacting into an anaerobic environment.
Yes, beneficial fungi reach much deeper than roots due to the higher penetrative ability of hyphae and they can still extract stuff from whatever depth they reach.
Long term I want to be able to do what the guy in the video is doing but with out all that shoveling...
And yeah seems like an awful lot of work aha
I'd imagine just getting a bull dozer or something, digging a whole lot of deep rows.
Then putting a sign in my neighbour for everyone to just come dump everything in the ditches, throw some wood on, light it up and repeat several times.
I saw that they are attempting synthetic stuff too which I might research later.
Some useful tips in this Reddit thread -> https://www.reddit.com/r/Permaculture/comments/1558h7/terra_...
Bamboo sounds like something worth investigating.
If you tell me which subject you're trying to learn more about I could recommend something. There's not really any text that covers that field broadly, you might start with a soil science book - I'd recommend Soil Science Simplified as intro or The Nature and Properties of Soils for a complete in depth text. Those won't tell you anything about nursery soils though, only field soil.
I added my email to my profile, feel free to hmu.
I don't have a specific interest at the moment, but have been more curious about this area recently after getting into regen ag podcasts.
https://www.youtube.com/watch?v=goUfl4x8URc
Essentially all of the permaculture advice for breaking up clay appears to be failing on her hardpan, so she's started using broadforking, which is a sort of compromise between tilling and building soil from the top down. The speaker in this video is being a little more aggressive with the broadfork than most people suggest. The idea is to open the subsoil without blending the upper layers together, resulting in the organic matter-consuming bacterial bloom you get with tilling.
One variant of keylining accomplishes a similar trick on an even smaller scale: you put one long slice into the ground. Water and organic matter seep into that cut and fan out from there.
IMO it really depends on what you're trying to grow. I live in the tropics and there are a lot of tropical plants that do indeed thrive when the soil is heavy on the organic matter. I suspect it depends on how far/long these tropical plants have been bred away from their rainforest origins.
Gardening is actually quite hard in this regard. Everyone is always sharing tips and tricks, for different crops, different species of said crops, different climates, different soils, different hemispheres, different sides of a mountain etc
I think there will be a cool database where you can filter by those factors one day but not sure we are quite there just yet.
Think Waze, for plants. We're about to launch on ProductHunt and HN, if you're interested you can check us out at https://greg.help.
Edit: Checked it out
Will install it and run it on my office plants.
Outside I am a dirty gardener and tend to just let things run it's course so won't help me much there.
It's really conventional farmers concentrating on annuals that want something different. They're growing prairie plants.
I can't help but wonder if his knowledge applies specifically to cases where chemicals like fungicide are used. There are quite a few species of soil fungus that are beneficial to plants, including root protection, but these can be wiped out by fungicides, leaving a blank slate for harmful fungus and other pests to take hold. So it would make sense that if there were no beneficial fungus present, then organic matter would be a rot threat.
With the exception of orchardists (whom some of us think doing everything wrong that you possibly can), modern agriculture concerns itself with prairie plants. Where natural woodland fauna can and do mix decaying logs into the soil column, in a prairie it will mostly be decaying roots (and especially decaying root hairs). The kind of rot going on is a bit different.
That said, saprophytic fungi are generally held to leave living tissues alone. There are exceptions of course, but having decaying woody matter in the soil is not a death sentence.
gardeners' advice that is along the lines of "what you do is wrong, what i do is right" is generally not very good, and you can feel fine telling them thanks on moving on with your life.
Worms!
they say you have to build up an entire ecosystem of life in your soil to attract the most worms.
I'm trying to find more ways of attracting them but it's hard to get specific studies that show things in a quantifiable way from the gardening community. Some say leaves on the surface attract worms, some say it's composted things, some say it's compost that hasn't completely been broken down yet. But, I have yet to see studies that show precisely the percentage of worms increased by various types of organic matter. What's the optimal approach? other than just adding more organic matter.
i'm adding as much organic matter on top as I can from a variety of sources. but, it'd be great to get some actual specifics on what's most effective.
An extra thing that helped was to take some of the worm organic matter (it was a trailer full of well rotted donkey manure) and stir it into my compost heaps. My compost heaps then also got infected with worms.
These days I do all my gardening in a 50/50% volumetric mixture of perlite and coco coir (buffered with calcium and magnesium). With a small amount of pH adjusted hydroponic nutrient and a watering can, the results you can achieve are just incredible, absolutely no comparison. Plus it's completely pest free so you aren't dragging in mite eggs, and fungus gnats.
Never using potting soil again, and anybody still using it should really reconsider. It's insanely counter-intuitive just how well plants can grow in something as inorganic as perlite. It just doesn't look like it should work.
A generic one/two part hydroponic fertilizer is sufficient for house plants. There's some coco coir specific ones but I usually water with a standard hydroponic mix at something like 50-70% of the manufacturer recommended concentration and every few waterings I'll do a flush with plain water (this stops fertilizer salts from building up).
I also recommend having calmag nutrient on hand, you can use it to buffer raw coco coir: https://www.youtube.com/watch?v=OQi8AMMIyyA and deficiencies are rather common.
It sounds complicated but it's super forgiving, zero mess, zero bugs, and plants absolutely thrive it in it. Oh and coco coir comes as pressed bricks which makes it convenient to store.
The root washers say that by removing all media that the sapling was grown in will give the roots more "incentive" to move into the native soil and thus it will establish quicker.
Whereas the anti-washers say you are slowing the establishment by washing away the helpful microbes as described in the article.
Then there are the people who say, DO wash the roots, but save the water. Plant the tree bare-root, but fill the hole with 50% of the saved water, and use the rest to top-water over the next few weeks. The idea is to get the benefits of bare-root planting along with saving the beneficial organisms.
The reason I ask is that my yearly tree just arrived in the post and I've yet to put it in the ground. I'd love to know what the current thinking is.
A little rule I follow is;
If the plant already looks quite unhealthy, I prefer to just put it as is straight into the ground, feed it and water it. It will take longer to recover but I believe it minimises the risk of outright killing it.
If I get a very healthy plant, I will play around with it more, slice its roots, rinse it out, make a soil mix for the new roots etc
This is completely speculative but the best results I've had so far.
Get like 9 of the same plants at the same point in the life cycle, wash 3, leave 3 and do the 50\50 for 3. Compare results.
If it's as big a deal as people make it out to be, it should be obvious, no?
But I do like a good experiment! And my neighbours garden is quite bare. Now you got me thinking...
Bare root plants never have this problem.
There is definitely a tendency of trees to behave as if they are in a pot when they encounter a huge change in soil medium. The dead tree I dug up this spring had virtually no roots outside of the original cone section of the pot it came in.
The other problem, especially with bushes, is they often put those little plastic time release fertilizer beads into their soil mix and so I'm putting microplastic into my yard. Often the roots are too fibrous to get all of the beads. I sometimes get the smaller plants because of this.
I don't actually 'wash' though, I use a chopstick to tease the dirt away from the roots. They're still coated.
Bare root plants do sometimes have issues getting started but I will only be ordering seed or bare root from now on.
I think that you don't want the rootball to be limited to the old pot outline, so opening it up a bit gently (so a few shakes and a little digging around) and encouraging a bit of a spread of the roots is the best way to go.
You might incentivize the tree, you might kill the tree... I don't think that this is a good plan :)
First we might look at dirt, but that doesn't quite pan out; where does the mass come from, and how would it be replenished? We don't see gaps slowly start forming around roots, and dirt doesn't just build up in other places, so that's probably not it.
Next we might look at water, but water is only made of hydrogen and oxygen, and the oxygen is released. The water also brings in nutrients, but there's no way it brings in enough to generate the majority of a trees mass.
So there's only one place left, which is never anyone's first guess and almost never crosses anyone's mind at first glance: air. It's around this point that most people realize that a majority of a tree is carbon, which all comes in from the air as carbon dioxide.
The mathematics of weight loss https://youtu.be/vuIlsN32WaE
The correct answer is water though, not air. Air only accounts for the Carbon content of the tree, which is a big part, but still a minority.
First, a live tree contains a lot of water (30-50%), that's why you need to let wood dry a lot before burning it.
And there's something else:
> Next we might look at water, but water is only made of hydrogen and oxygen, and the oxygen is released.
Not all oxygen is released. All oxygen contained in a plants molecule (mostly cellulose and hemicellulose, which are polymers of glucose, and lignin) comes from water. And there's a lot of it: there's as much Oxygen as Carbon in a glucose molecule.
Plant carbohydrates are made directly from CO2 in the Calvin Cycle.
The Calvin Cycle is the source of all of the carbohydrate building blocks in the plant, and I’m pretty sure that oxygen from H2O does not enter the equation, just CO2 and some enzymes and cofactors.
If so, the vast majority of the mass is from the air.
(H might originate from water but its mass is pretty trivial compared to C and O)
"Water Is the Source of the Oxygen Produced by Photosynthesis" (and CO2 is the source of the oxygen in carbohydrates)
http://www-plb.ucdavis.edu/courses/bis/2A/bis2A-F11/Photosyn...
But where does all that excess oxygen go then? (the O/C ratio is 2 in C but ~1 in carbohydrates).
I would have been wrong, mind blown lol thanks.
To head down the rabbit hole of soil health even further, learning about increasing the cation exchange capacity(CEC) affect on plant health has been fascinating.
In fact, if you try to plant venus fly trap in rich soil, it'll probably die.