When does our trees actually feed?

[fredman]

As I have it, plants only feed when they're in need of nutrients. They sometimes take up only a certain nutrient...or nutrients that they're in need of at that time.
They certainly don't feed all the time. That got me thinking. If I fertilize often...because i'm using a open soil, how much is actually taken up, and how much flows right through. Not a big deal really, but I would still like to know, and make the best of things. Dyna Gro ain't cheap
That's why I like to add a organic part (bark) to my mix...and zeolite to. It apparently holds onto nutrients for longer.

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[just.wing.it]

Hey @fredman, what's up!

I like to feed often as well, for the same reason. But I think late spring and early fall may be the times that the tree may use the most.....I think.

 

[Wires_Guy_wires]

Plants feed only when they need it, but a certain base level in the soil is good for osmotic pressure and water balance.

Three weeks before growth starts, until fall when growth stopped.

But you're right! A lot of it washes out straight away. That's why it can be a strategy to water first with water to saturate the soil for humidity/water, then water with nutrients for the salt levels.

I think with our soils and relatively agressive watering schedule, we wash out about 80% of the nutrients we provide. Part of the reason why I get the cheapest shit out there, and have some more expensive super nutrients that I add when I see deficiencies.

 

[Potawatomi13]

Hmmm..... From posts here seems some(all?)trees take up excess amounts of some elements that can cause problems. Strong suspicion is tree takes up whatever dissolved in H2O whether needed or not.
This said personally have used 20-20-20 fertilizer several years. Happy trees. No problems. Perhaps use lower percentages for trees refined or getting refined so not quite so happy.

 

[Bnana]

That is not correct, trees can very well regulate what they take up. Only at high levels of nutriënten trees have a problem as the osmotic value gets to high and it extracts water from the roots. Ammonia is an exception, if that is in a high concentration trees have a hard time keeping it out (actually a reason why trees such as oaks are doing poorly in areas with very intensive farming and high NH4 concentrations).
I also use the cheap stuff as the tree knows best. You do not need high concentrations, but it has to be available in the growing season.

 

[penumbra]

I foliar feed frequently and have never seen a plant burn because of over fertilization. My first job was at a nursery when I was 13 and this is what we did. I am 72 now, and this is what I still do.

 

[Leo in N E Illinois]

Both. Trees absorb via osmosis simple nutrients in the water. Ions, like nitrate, potassium, calcium, salts in general, are taken up via osmosis, and the plants in general don't keep these salts out. The exception are the "salt adapted" plants and trees that tolerate salt spray from the oceans, or salt soils. Plants also actively take up specific nutrients. Certain larger molecules are actively transported, including amino acids and some sugars and certain chelated metal complexes.

In general plants can not keep out of their tissues most simple inorganic fertilizers, hence the caution to not over fertilize. Retaining soluble nutrients is difficult, hence only certain species can survive in ultra low dissolved solids water, (bogs and other nutrient poor communities).

My solution is frequently feeling at dilute concentration.

 

[Bnana]

The concentration of potassium is typically a lot higher in the plant than outside, K+ concentration in the soil solution may vary widely from 0.01 to 20 mM, plant cells have 80–100 mM in the cytoplasm. That is of course impossible with osmosis. Plants do that by actively taking potassium in with transporter proteins (high affinity transport system). They also have a more passive system using dedicated cation channels (low affinity transport system) but that only works when the outside concentration is high. The same is true for nitrate, different proteins, same mechanism. For calcium it is less clear (at least to me) but there are cation channels that allows the uptake.
Overall nutrient uptake is very much an active process regulated by the plant, through specific proteins.
If concentrations in the plant are too high they can be pumped out but that is costly, that happens with NH3/NH4+ in soils with high concentrations (there is a passive system for ammonia so too much can come in). There is a limit to how much a plant can pump out and at a certain point it fails.

Salt adapted plants are good in expelling sodium and chlorine that leak into the plant and can grow at high osmotic pressures where other plants would lose too much water. But that is a related but very different topic.

(Of course mycorrhiza play a big role as well, with ectomycorrhizal and ericoïd-mycorrhizal fungi being very good in the uptake of nitrogen and AMF for phosphate but that is also ultimately regulated by the plant)

 

[penumbra]

Though I only have a rudimentary understanding of what you all are talking about, I find it fascinating.
But I can't help but believe that plants, in some way, are smarter than all of us. We depend primarily on our learned understandings while plants directly exhibit their bond to the intelligence inherent in nature.

 

[Bnana]

You're doing very similar things.
You're also continuously regulating the pH of your blood, replacing old cells with new ones, maintaining crucial electrical potentials in your nerve cells and thousands other things like that, you're just not aware of it.

 

[penumbra]

You're doing very similar things.
You're also continuously regulating the pH of your blood, replacing old cells with new ones, maintaining crucial electrical potentials in your nerve cells and thousands other things like that, you're just not aware of it.

I completely understand. My comment was rather tongue in cheek regarding the intelligence inherent in nature. It has been a serious study of mine for several decades.

 

[Bnana]

I understand, but you shouldn't feel inferior, you're not less intelligent than your bonsai.

 

[penumbra]

I understand, but you shouldn't feel inferior, you're not less intelligent than your bonsai.

Wow! That is a loaded concept............ and highly debatable.
I desire is to be one with everything, not superior or subservient to it.
Boy ........... have we ever gotten off track for this thread. I apologize and will be mute on this henceforth, at least in this thread.

 

[Shibui]

As I have it, plants only feed when they're in need of nutrients. They sometimes take up only a certain nutrient...or nutrients that they're in need of at that time.
They certainly don't feed all the time. That got me thinking. If I fertilize often...because i'm using a open soil, how much is actually taken up, and how much flows right through. Not a big deal really, but I would still like to know, and make the best of things. Dyna Gro ain't cheap
That's why I like to add a organic part (bark) to my mix...and zeolite to. It apparently holds onto nutrients for longer.

There's a lot of conflicting opinions on fertilizer. This thread has brought out some sensible sounding explanations but I have no idea whether any or all have been proven correct.
I am aware of the following:
A lot of nutrients are leached through the soil by water and so lost to our potted plants. This seems to be inevitable, even when using high CEC (organic or zeolite) in the mix. You may be able to reduce leaching but I don't think it is possible to eliminate and still provide the other conditions the plant needs.

Many plants may feed more than some understand. It is generally accepted that plants do not use nutrients in winter. A few years ago one of our leading bonsai growers recruited others all over Aust to trial winter feeding for pines. The results show much better health and growth when JBP are fed right through our winters. I now fertilize all evergreen plants (at reduced rates to compensate for slower growth) through winter. Efficacy may vary depending on how cold winter gets in any area.

Some plants appear NOT able to regulate uptake of nutrients. Proteacea family have evolved to live in low P soils and develop special roots that are super efficient at finding and mobilizing the little P available. If we provide 'normal' levels of P to these plants they overdose and die, indicating they have no mechanism to regulate uptake of P.
Plant nutrient references include symptoms of nutrient toxicity in plants. I'm not sure of the mechanism for such damage but plants can certainly be affected by excess or imbalance of nutrients.

I also follow the 'cheapest available nutrients' model. No point in paying high price when plants are only interested in the ions, not the source of them or how much you paid, and so much is just lost.
Flip side of this is that we need to also be aware of where those leached nutrients end up. Fertilizer leaching from our plants and gardens is implicated in waterway decline - algal blooms, fish kills, etc so we do need to reduce fert runoff as much as possible and make sure that runoff water is filtered as well as possible before ending up in drains.

 

[rockm]

You all do know that plants make their own food. They don't "feed" on fertilizer...just sayin...When you fertilize them, you're not "feeding" them. You're replenishing the necessary nutrients they need to complete the photosynthetic process...

 

[HorseloverFat]

Cool thread!!!!

I agree with (and learned some) everything said.

I, personally, am a HUGE practitioner and advocate of “foliar feeding”.. I use Drammatic... I ALSO use a “Balanced” granular for MOST things...

I have acid and lime loving granular for the roughly 1/4 of my plants with specific tastes BEYOND what is attainable with balanced-granular and fish/kelp foliar fertilizing

 

[WNC Bonsai]

Plants will also take up scarce nutrients such as nitrogen and trace elements in excess of their needs and store it for later use in a process known as luxury consumption. They also will extract scarce nutrients from the leaves in the fall and move them into storage, while other elements that are readily available in the soil will just be left in the leaves to leach out on the ground. In water quality studies we often saw large fluxes of potassium in streams in the fall as a result but in natural systems very little nitrogen makes it past the root zone. Interestingly on the other hand potassium will also be taken up in excess during active plant growth since it is needed in relatively large concentrations in cells.

 

[fredman]

You all do know that plants make their own food. They don't "feed" on fertilizer...just sayin...When you fertilize them, you're not "feeding" them. You're replenishing the necessary nutrients they need to complete the photosynthetic process...

This is the most important thing I learnt about fertilization. I wanted to include that in my OP, but thought it would distract from the question I had.
Thanks for pointing out the fact though. I think it's something every bonsai enthusiast needs to know and understand well !!!

 

[Crawforde]

Differing and changing mineral chemistry in the soil and water (independent of pH) can change the way certain plants grow and flourish. Most have reasonably wide tolerance levels, but others can have diminished health or delayed flowering or poor root growth, or…
So, watch your plants, and change your process as needed.

 

[Wires_Guy_wires]

You all do know that plants make their own food. They don't "feed" on fertilizer...just sayin...When you fertilize them, you're not "feeding" them. You're replenishing the necessary nutrients they need to complete the photosynthetic process...

They generate their own energy. But "food" is so much more than just calories.

I think we should move away from the 'plants make their own food' idea, because it's ignoring all other roles nutrients can have and it relies on the idea that food=energy. Food is more. Just like we can't survive on sugar and water alone, plants can't either.
Nutrients also help plants with stopping or diverting their photosynthetic processes, help build enzymes that aid in defense mechanisms and even regulate their rhizosphere pH, along with a couple hundred or more non-energy related things. While all of these function include carbon and burn energy in some form or shape, without the proper nutrients they can't do their part in the plant body.

I therefore propose we start saying something like "plants make their own energy/calories" instead of "plants make their own food".