Input needed from a experienced RDWC/UC grower

While I'll not tell you that you're wrong I'll present some evidence for why I believe plants do not simply pick what they need from a recirculating hydroponic solution. For this I'll reference a paper from an 18 year study into nutrient management in recirculating hydroponics. For the record the paper and article you reference both talk about uptake from a soil solution. As I can't be exactly sure uptake is different between hydroponics and soil, I have though been in these discussions with an old friend with a PhD in plant physiology, and we've found contradicting findings in studies regarding uptake from soil solutions and studies regarding uptake from hydroponic solutions, so I continue to base my knowledge on the studies concerning hydroponics only.

First I'll derectly quote the paper from the study I mentioned, conducted by Professor Bruce Bugbee at the university of Utah.

Managing nutrients by mass balance.
During the past 18 years, we have managed nutrients in closed hydroponic systems
according to the principle of "mass balance," which means that the mass of nutrients is
either in solution or in the plants. We add nutrients to the solution depending on what we want the plant to take up.
Plants quickly remove their daily ration of some nutrients while other nutrients
accumulate in the solution. This means that the concentrations of nitrogen, phosphorous,
and potassium can be at low levels in the solution (0.1 mM or a few ppm) because these
nutrients are in the plant, where we want them. Maintaining a high concentrations of
nutrients in the solution can result in excessive uptake that can lead to nutrient imbalances.
For example, the water removed from solution through transpiration must be
replaced and it is necessary to have about 0.5 mM phosphorous in the refill solution. If the
refill solution was added once each day, the phosphorous would be absorbed by the plant
in a few hours and the solution phosphorous concentration would be close to zero. This
does not indicate a deficiency; rather it indicates a healthy plant with rapid nutrient uptake.
If phosphorous was maintained at 0.5 mM in the recirculating solution, the phosphorous
concentration in the plant could increase to 1% of the dry mass, which is 3 times higher
than the optimum in most plants. This high phosphorous level can induce iron and zinc
deficiency (Chaney and Coulombe, 1982).
Feeding plants in this way is like the daily feeding of a pet dog, some dogs would be
seriously overweight if their food bowls were kept continuously full.

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So from his experiments and testing of leaf, stem and tissue he found that should there be available more of certain elements than required, the plant can continue to remove it from the hydroponic solution to the point it will reach excessive amounts in the plant which can cause imbalances with other nutrients.

From this I conclude that for an indoor grower providing a good environment for optimal growth and transpiration; it is imperative to make available in the recirculating solution only the amounts of nutrients needed for optimum growth, and not more, therefore avoiding excess within the plant.

I'm not saying the science is wrong that you've referenced, or that there's no upper limit, but nutrient excess within hydroponically grown plants is real, and is a result of uptake past the point of there being optimal amounts already in the plant. With Nitrogen being our example here, small root systems, stretchy weak stems and branches and possibly delayed flowering are all things a grower might want to avoid.
Therefore I would say plants don't just "pick what they need".

It may be semantics to a point, but a lot of learner growers, especially now home mixing nutrients is gaining popularity, will glean information in it's most simple form.

Peace
BL

southernguy99 said:

if the ratio was 90% apples and 10% oranges, you'll probably have a hard time getting oranges, and 2, will there be enough to fill your needs, well by letting your rez go for weeks on end that basically what happens,

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Billy Liar said:

Different nutrient elements have different forms and rates of uptake/removal from solution.

NO3, NH4, P, K, Mn: active uptake, fast removal.

Mg, S, Fe, Zn, Cu, Mo, Cl: Intermediate uptake.

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Billy Liar said:

From this I conclude that for an indoor grower providing a good environment for optimal growth and transpiration; it is imperative to make available in the recirculating solution only the amounts of nutrients needed for optimum growth, and not more, therefore avoiding excess within the plant.

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Seems like your both advocating for weekly res changes considering the ratios of nutes matter to both of you though maybe for slightly different reasons or perhaps maybe the same reason, perhaps just a lil further research may uncover you're both talking about the same thing just different parts of it, lol but maybe not.. Either way thanks for the info now I better research.. But then again probably not lol...
.
Soil is just a medium right? The plant needs water but the water in nature is saturated with elements that it physically surrounds, so in my limited knowledge it seems hydroponic and soil are principally the same, it's in the way the nutes are distributed to the water that's different? One water solution is controlled in a lab, while one water solution is controlled by the surroundings being dissolved into it? Makes me think you're both talking about the same thing but getting hung up on differences in the 2 areas you're observing, one at the molecular level at the roots, one at the macro level of mass diffusion? Buuuut then again, it might just be wishful thinking lol

Billy Liar said:

Bruce Bugbee at the university of Utah.

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Go UTES!

JSheeze said:

Soil is just a medium right? The plant needs water but the water in nature is saturated with elements that it physically surrounds, so in my limited knowledge it seems hydroponic and soil are principally the same,

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Soil is alive with fungal and bacterial organisms breaking down material organically, unless someone runs soil as a medium and uses chemical nutes, the more away from organic the more away from soil.
You can't run organically the same in hydroponics. So they are similar, but not the same. Hydroponics gives the plant what it needs to grow and bloom. In soil there is a lot more going on and things available to the plant that only soil can provide. I think it's pretty common knowledge that hydro grows faster and yields more than soil, but soil provides better color, and flavor.

Big Perm said:

Soil is alive with fungal and bacterial organisms breaking down material organically, unless someone runs soil as a medium and uses chemical nutes, the more away from organic the more away from soil.
You can't run organically the same in hydroponics. So they are similar, but not the same. Hydroponics gives the plant what it needs to grow and bloom. In soil there is a lot more going on and things available to the plant that only soil can provide. I think it's pretty common knowledge that hydro grows faster and yields more than soil, but soil provides better color, and flavor.

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Ya I agree I'm saying that ultimately not dependepent on the process the elements are provided, but that ultimately the plant gets its up-take through a water based solution. The nutes provided are either by biological means or man-made. But maybe I'm wrong, maybe they do suck up part of the micro ecosystem, maybe they do suck up the fungus and bacteria? Is that what you're saying?

From my understanding the fungus and bacteria live near the root zone and their "waste" output are nutrients the plant can use. Just a symbiotic relationship.
Read that fungus actually extends the micro hairs of the roots in soil so that they are essential longer and therefore uptake more nutrients.
None of that matters in hydro though. The nutrient uptake of water is too good to need help from bacteria and fungus, besides keeping rots and stuff away. Last half of that is opinion btw.

JSheeze said:

maybe they do suck up the fungus and bacteria? Is that what you're saying?

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I'm just saying that organics provides a nutrient environment that can't be replicated by chemicals. I'm not a scientist, but there is a reason that hydro and organic dirt taste different, and I believe that is why.
I'm not saying one is better than the other. I've grown both. More recently I'm going back to dirt because I'm not after yield and speed anymore.

Big Perm said:

I'm just saying that organics provides a nutrient environment that can't be replicated by chemicals. I'm not a scientist, but there is a reason that hydro and organic dirt taste different, and I believe that is why.
I'm not saying one is better than the other. I've grown both. More recently I'm going back to dirt because I'm not after yield and speed anymore.

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That's kinda how I feel when I hear guys say all they use is maxi bloom. I'm sure it'll work as a stand alone, but I think all those other bottles that are sold are the extra efforts in trying to closer mimic what happens optimally in nature. I'm sure some is marketing "magic water" but I've seen some pretty neat looking plants when they use all the bottles lol

I use to grow in soil exclusively, dabbling w hydro for a second haha...

Big Perm said:

I'm just saying that organics provides a nutrient environment that can't be replicated by chemicals. I'm not a scientist, but there is a reason that hydro and organic dirt taste different, and I believe that is why.
I'm not saying one is better than the other. I've grown both. More recently I'm going back to dirt because I'm not after yield and speed anymore.

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Ford and Chevy kinda thing lol

JSheeze said:

I'm sure some is marketing "magic water"

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I bet it's more like,

I'm sure 95% is "magic water" marketing.

shawnery said:

I bet it's more like,

I'm sure 95% is "magic water" marketing.

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Lol that's what I've heard

Billy Liar said:

While I'll not tell you that you're wrong I'll present some evidence for why I believe plants do not simply pick what they need from a recirculating hydroponic solution. For this I'll reference a paper from an 18 year study into nutrient management in recirculating hydroponics. For the record the paper and article you reference both talk about uptake from a soil solution. As I can't be exactly sure uptake is different between hydroponics and soil, I have though been in these discussions with an old friend with a PhD in plant physiology, and we've found contradicting findings in studies regarding uptake from soil solutions and studies regarding uptake from hydroponic solutions, so I continue to base my knowledge on the studies concerning hydroponics only.

First I'll derectly quote the paper from the study I mentioned, conducted by Professor Bruce Bugbee at the university of Utah.



So from his experiments and testing of leaf, stem and tissue he found that should there be available more of certain elements than required, the plant can continue to remove it from the hydroponic solution to the point it will reach excessive amounts in the plant which can cause imbalances with other nutrients.

From this I conclude that for an indoor grower providing a good environment for optimal growth and transpiration; it is imperative to make available in the recirculating solution only the amounts of nutrients needed for optimum growth, and not more, therefore avoiding excess within the plant.

I'm not saying the science is wrong that you've referenced, or that there's no upper limit, but nutrient excess within hydroponically grown plants is real, and is a result of uptake past the point of there being optimal amounts already in the plant. With Nitrogen being our example here, small root systems, stretchy weak stems and branches and possibly delayed flowering are all things a grower might want to avoid.
Therefore I would say plants don't just "pick what they need".

It may be semantics to a point, but a lot of learner growers, especially now home mixing nutrients is gaining popularity, will glean information in it's most simple form.

Peace
BL

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Hey BL for the most part I agree with this, I think in general terms were on the same page we just see things a little bit technically different , first I'm familiar with Bugbee and the paper you posted. I think that paper was written somewhere around 2000-2002

The 2 studies I post was in soil your correct, mostly because there is many more studies done in soil and the science is much more clear, studies for closed hydro system is lacking , now that it is legal in canada and more in the USA I hoping there will be much more done.

As far as soil goes there has been many studies done about plants and the selectivity of nutrient uptake, even the United States Department Agriculture has stated this and published papers on it, its really a lot of science published on this so I really think its been proven. But in saying that its not absolute

There is a lot of factors involved and still some unknown ones I'm sure. I seen studies that showed a plant out side under normal conditions that the plant was selective, but in the same soil in a pot its not, it loses that ability. way to many reasons to list but, root size, quality of roots, the percentage of soil occupied by the roots, concentration of nutrients, the balance of negative vs positive ions, if the soil has a negative charge or positive charge , RZT ( root zone temperature ) There is a study on this specifically that shows if optimal temp is not maintained the roots will not send ions up the plant or send everything at once if it to hot. plus so much more we could talk about cation exchange or anion exchange capacities etc. the better the grower balances these the easier the plant will adapt and grow more naturally, the less balanced the harder time the plant will have.

now we know when you go to hydro everything is more complicated with the above, thats why you see people saying soil is more forgiving, so nutrients act differently in water, In water diffusion coefficients for ions are practically the same , but in soil the diffusion coefficient is a lot different because of how the ions acts with the soil, nitrate is not absorbed by soil , phosphate is highly absorbed, that reduces diffusion coefficient. so in water is much more important that these ions remain balanced.depending on the grow stage of the plant, the concentration of each cation and anion in the solution changed a lot. now I'm not going to go to deep into this, but this goes right back to what a few of us are saying, this is why weekly flushes are so important, why a proper balanced nutrient solution is so important, ph , temperature, lighting , humidity etc.

So in the last couple years there was a study done that shows that when everything is keep in check a plant in a closed hydro system has the ability to selectively deplete or not use / rate and extent of selected ions out of the solution during the plants growth stages, they done this by monitoring each nutrient specifically on a daily basis, measuring the each ion and replacing each one as need. The study also showed the EC is an insufficient or incorrect way to monitor a hydro system, simply because it only monitors total and not each individual ion, it does not show the imbalance or deficiency in each specific ion. thats why weekly water changes are so important with a proper balance solution because it rests the balance of the solution, if you have the ability to monitor each ion separately and replace each one as needed then water changes would be as important.

Anyhow I hope you all have a merry Christmas

Its threads like this that made me join this forum,informative and a pleasure to read.
Looking forward to more in the new year!

Why are you dudes pissing in the op thread... He asked for info in setting up a small undercurrent.. Nothing on this page addresses that question..

mytwhyt said:

Why are you dudes pissing in the op thread... He asked for info in setting up a small undercurrent.. Nothing on this page addresses that question..

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The OP was wrapped up at post #10. On post #11 he got into lights, and things moved on. I agree that nothing on page 4 addresses the original question. We'll consult with you next time as to when to open another thread.

How do you ever get you head up your ass with that big perm? The hairs not doing it, maybe you should consider wearing a little.black face.. Be sure to check with me next time..

myke said:

Its threads like this that made me join this forum,informative and a pleasure to read.
Looking forward to more in the new year!

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Welcome to the forum. There's a lot of good info here, once you know what to look for. This is how it goes here for the most part, though.