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bobrown14

Grow Journal of the Month: Dec 2017
Science Bomb on "flushing" aka leeching. Pay attention to highlighted area.



Cations can be classified as either acidic (acid- forming) or basic. The common acidic cations are hydrogen and aluminum; common basic ones are calcium, magnesium, potassium and sodium. The proportion of acids and bases on the CEC is called the percent base saturation and can be calculated as follows:




Total meq of bases on exchange sites

Pct. base =(i.e., meq Ca++ meq Mg++ + meq K+)
saturation ------------------------------- x 100
Cation exchange capacity


The concept of base saturation is important, because the relative proportion of acids and bases on the exchange sites determines a soil's pH. As the number of Ca++ and Mg++ions decreases and the number of H+ and Al+++ions increases, the pH drops. Adding limestone replaces acidic hydrogen and aluminum cations with basic calcium and magnesium cations, which increases the base saturation and raises the pH.

Relationship Between CEC and Fertilization Practices
Recommended liming and fertilization practices will vary for soils with widely differing cation exchange capacities. For instance, soils having a high CEC and high buffer capacity change pH much more slowly under normal management than low-CEC soils. Therefore, high-CEC soils generally do not need to be limed as frequently as low-CEC soils; but when they do become acid and require liming, higher lime rates are needed to reach optimum pH.

CEC can also influence when and how often nitrogen and potassium fertilizers can be applied. On low-CEC soils (less than 5 meg/20000g), for example, some leaching of cations can occur. Fall applications of ammonium N and potassium on these soils could result in some leaching below the root zone, particularly in the case of sandy soils with low-CEC subsoils. Thus, spring fertilizer application may mean improved production efficiency. Also, multi-year potash applications are not recommended on low-CEC soils.

Higher-CEC soils (greater than 10 meg/100g), on the other hand, experience little cation leaching, thus making fall application of N and K a realistic alternative. Applying potassium for two crops can also be done effectively on these soils. Thus, other factors such as drainage will have a greater effect on the fertility management practices used on high- CEC soils.
 

Emeraldo

Well-Known Member
Enjoyed reading that, Bob, and not just the emphasized phrases. Soil science is fascinating, and leeching in low-CEC soils is a real problem for farmers in the field. It seems to me this is a problem for the cannabis grower who grows outdoors in the ground, just as it is for the corn farmer. And I have the impression that you grow in the ground near your bog. What does this tell us about growing cannabis in pots at home, where we can mix and test and amend our supersoil?

I don't think cation leeching is foremost in the mind of the cannabis grower who flushes the soil in 15 gallon pots before harvest to improve taste. Or the pot grower who flushes before flowering starts to adjust the plant to flowering nutrients. By washing excess nutrients out of the soil -- and, yes, out of the roots -- leeching might occur. Of course, any cation leeching in my fabric pots might also be compensated next season with amendments of say calcium (your oyster shell mix, of which I bought some for next year, thank you for the tip).

The main issue raised here is the risk of pushing pH down too far. With low-CEC soils, losing Ca and Mg leads to lower pH, which can be corrected with lime. Uncorrected leeching will make the soil in your field too acidic. But when it comes to flushing soil in a 15 gallon pot -- if a grower wishes to flush -- all this simply underscores the need to flush with water having the right pH for the cannabis plant. Flushing with water having the correct pH would minimize the risk of leeching the soil in my 15 gallon pot, which, if it did occur, could be corrected with lime and other amendments for the next grow.
 

bobrown14

Grow Journal of the Month: Dec 2017
Emeraldo,

What you say is true. Leeching is a thing in sandy soils with low CEC and AEC.

What we are doing growing in containers in soil, most are running high CEC soil.
The way to test that is to get a soil sample.

If there's rock dusts in the mix its going to raise the CEC to VERY high levels.

Think about clay and how it is formed and why it's important for healthy soils.

This is why many of us add rock dusts to our soil mix. This is taking the place of a naturally occurring clay / clay mix that are in many soils in the ground around us.

We container growers try and mimic this with our soil mixes.

Another little info bomb:

"What are exchangeable cations?

The clay mineral and organic matter components of soil have negatively charged sites on their surfaces which adsorb and hold positively charged ions (cations) by electrostatic force. This electrical charge is critical to the supply of nutrients to plants because many nutrients exist as cations (e.g. magnesium, potassium and calcium). In general terms, soils with large quantities of negative charge are more fertile because they retain more cations (McKenzie et al. 2004) however, productive crops and pastures can be grown on low CEC soils.
The main ions associated with CEC in soils are the exchangeable cations calcium (Ca2+), magnesium (Mg2+), sodium (Na+) and potassium (K+) (Rayment and Higginson 1992), and are generally referred to as the base cations."


This electrostatic force is why flushing soil to get rid of excess nutrients is basically just washing away the micro-organisms beneficial to plant growth.

The micro-organisms don't have a life boat but they do have hyphae to hold onto. Like a life rope when the floods come. They will come.

I wood say flushing can be of some use. But that wood be when you have your soil tested and know the CEC, AEC and soil pH as tested in a lab along with all your base nutrient levels. Likely be where indoor professional cannabis growing is headed as long as there's money there to support the work.

The thing with soil is most of the nutrients are not soluble and require micro-organisms to break them down into soluble form. Trying to wash them away along with the micro-organisms just doesn't make a lot of sense to me.

Best to start off with a balanced soil and not need to add in nutrients because you're soil mix is lacking something.

Amendments are important.
 

Emeraldo

Well-Known Member
There is a good discussion of flushing in Ed Rosenthal's Marijuana Grower's Handbook (2010), pp. 162-63, where he discusses fertilizer overdoses.

The science here is essentially the second law of thermodynamics, which states that in a solution the concentration of salts becomes equal throughout. In plant tissue, equilibrium is maintained via cell membranes and osmosis. "Normally, plants maintain a higher salt concentration than the surrounding environment so they easily absorb water. When the solution outside the plant becomes more concentrated than the solution inside, the plant cannot draw water and wilts."

That is what happens with a fertilizer overdose. The soil has such a high concentration of salts that the plant cannot absorb water and a nutrient lockout takes hold.

Then Rosenthal says:
"To save plants suffering from toxic overdose of nutrients, run plain water through the system to flush out the medium so the nutrient concentration becomes diluted. When this happens, the porcess reverses and the plant is able to pull water inside, once again become turgid."

This may in fact be what happened to the plant of the OP. It wilted. So where did the heat discussion go? Maybe the plant was suffering from fertilizer overdose!
 

bobrown14

Grow Journal of the Month: Dec 2017
No not in soil.

Osmosis in soil is basically how water evenly distributes. Has nothing to do with fertilizers or salts. Plants have a vascular system to move water and nutrients up thru the plant. That process is capillary action. Pretty cool stuff.


What you quoted goes against all physics and plant biology.

Osmosis in plants works somewhat different than you explain.

Here's how osmosis works in plants:

"Plants absorb water and minerals salt from the soil with the help of root hairs. They absorb water by the process of osmosis. Osmosis is the movement of water molecules (solvent) from a lower concentration solution to a higher concentration solution through a semi permeable membrane "

"toxic overdose" = you screwed up and tried to kill your plant with too much fertilizer.

OK you might be able to save your plant with more water. But it's not removing much nutrients in SOIL OR from the plant. Specially soil with high CEC or even moderate CEC. It would have to be soil-less medium not soil medium.


Ok onto the 2nd law of thermodynamics.

I'm just going to post what it is and you can draw a conclusion.

"The second law of thermodynamics states that the entropy of any isolated system always increases."

Entropy:

"Entropy and the Second Law of Thermodynamics If a china mug is dropped on the floor and breaks into many pieces, we accept this as a normal process. If the mug were to put itself back together and jump back into our hand we would consider this a most abnormal process. It is the Second Law of Thermodynamics which provides the principle that governs the ordering of events. It can be said that it determines the direction of time. The Second Law of Thermodynamics can be stated in terms of the entropy of a system. The concept of entropy is used to describe the degree of order in a system."

I need more Orange Sunshine to make that leap Ed/you describe.

Maybe that's the source of the flushing paradigm. I dunno but it's clever. It sounds good.
 
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Emeraldo

Well-Known Member
Uhm, right. So Ed Rosenthal maybe is the source of all this garbage about flushing for the purpose of diluting a fertilizer overdose. But you think he's wrong and what he says goes against all plant science. That's what I thought you were going to say, but just wanted to give you a chance to recant and become a flusher.

But Dr. Ed is not alone. Just look around. There's Greg Green, too, in The Cannabis Grow Bible (2017) at pp. 262-63. The "soil flush" is an emergency procedure for returning the soil to about pH 7 after a spill or accidental pouring of too much fertilizer, maybe even in too high a concentration, into the soil. He devotes several pages to different situations and correspondingly different steps.

Greg Green is wrong too, I presume? Uh-huh, right.

Be well...
 
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bobrown14

Grow Journal of the Month: Dec 2017
Yeah dont really know what to say. Emergency flushing.. sounds like back tracking to me.

I get where the flush thing is coming from, Its just not what people think it is. Just trying to do my part to help folks understand better about some of the pseudo science and real science.

I mean we've been growing plants all our lives my wife and I, never did I ever see or hear of any of these weird practices until I started reading about how people grow weed.

Some practices are actually pretty bizarre.

It's like if a little works ok, well then lots works better??

For me, its try a little, and see how it grows and err on the side of caution. But that's just me.
 

Emeraldo

Well-Known Member
1827643
i need some serious help this happened after a 100-degree day and I don't know how to help it recover what do I do
This thread started out as a discussion of what was wrong with the plant in the picture. It emerged that the plant was in MIracle Grow soil, and the symptoms sound a lot like a fertilizer overdose. If Kokeman actually over-fertilized on top of the Miracle Grow slow-release chemicals in that killer soil, then it would have been enough to lock out water. Then, in the heat, wilted. Just like Dr. Ed said.

What happened to Kokeman? What happened to the plant?
 

bobrown14

Grow Journal of the Month: Dec 2017
Yeah dont really know what to say. Emergency flushing.. sounds like back tracking to me.

I get where the flush thing is coming from, Its just not what people think it is. Just trying to do my part to help folks understand better about some of the pseudo science and real science.

I mean we've been growing plants all our lives my wife and I, never did I ever see or hear of any of these weird practices until I started reading about how people grow weed.

Some practices are actually pretty bizarre.

It's like if a little works ok, well then lots works better??

For me, its try a little, and see how it grows and err on the side of caution. But thats just me.
 

Emeraldo

Well-Known Member
Yeah dont really know what to say. Emergency flushing.. sounds like back tracking to me.

I get where the flush thing is coming from, Its just not what people think it is. Just trying to do my part to help folks understand better about some of the pseudo science and real science.

I mean we've been growing plants all our lives my wife and I, never did I ever see or hear of any of these weird practices until I started reading about how people grow weed.

Some practices are actually pretty bizarre.

It's like if a little works ok, well then lots works better??

For me, its try a little, and see how it grows and err on the side of caution. But thats just me.
Ok, Bob, that is your view. I guess pot growers who grow in pots do this flushing thing sometimes, for various reasons, mostly to do with fert overdose and sometimes to do with pre-harvest prep. Growers like you who grow in the open ground do not flush because it is not possible to flush for them. Chacun a son gout. To each her own. ;)
 

Emeraldo

Well-Known Member

Emeraldo

Well-Known Member
Yeah dont really know what to say. Emergency flushing.. sounds like back tracking to me.

I get where the flush thing is coming from, Its just not what people think it is. Just trying to do my part to help folks understand better about some of the pseudo science and real science.

I mean we've been growing plants all our lives my wife and I, never did I ever see or hear of any of these weird practices until I started reading about how people grow weed.

Some practices are actually pretty bizarre.

It's like if a little works ok, well then lots works better??

For me, its try a little, and see how it grows and err on the side of caution. But thats just me.
Flushing to correct a fertilizer overdose is the primary example of when flushing is said -- by many professionals with a lot more credibility -- to help an overdose. The second is in prepping for harvest. Please re-read the thread, that was the primary point: correcting overdose. I have myself had experience with flushing and corrected nitrogen toxicity in a cannabis plant.

"Back-tracking"-- what do you mean by that?
 

bobrown14

Grow Journal of the Month: Dec 2017
You can actually run enough water thru a soil medium and LEACH off "some" added or extra Nitrogen.

This all depends on soil make up. This is why telling people that "flushing" soil will fix the problem. Well its actually chemistry at work and no 2 soils are the same so when water runs thru 1 mix it will leach out differently than another soil mix.

Flushing is not a "fix" for anything in soil. I will argue that with anyone. I've actually studied soil science a little bit.

What you are talking about with "fertilizer overdose" is simply called a chemical spill. Plain simple terms there. It's what it is.

Chemical Spills are NOT treated with excess water. This is bad advice likely even against your local environmental laws. It is here where I live.

This type of thing will become an issue as cannabis comes out of the closet and into main stream after prohibition is over. Going to be a good reason for government to step in and limit home growers due to polluting fresh water.

The best way would be to educate growers so they don't pollute the environment. Think of it on a larger scale. Not just me or you but our community and everyone doing the same thing.

Farmers have been aware of excess nitrogen getting into our fresh water supply for a very long time now.

Excess nitrogen is about all that you can "rinse" out and even that depends on your soil make up. Large amounts of SOM (soil organic matter) with a high CEC ratio will be able to hold onto that excess N (its chemistry). Soil-less medium is different and that's when it becomes an issue with the environment.

The only reason I debate this with anyone is because its going to become an environmental issue - likely already has in California and why they changed the laws and put all the small growers out of business. Instead of education and training, just call in the police. Simple minded and effective.

I prefer and more proactive approach like education.

Pretty simple really. Ask this:

"Do you think drinking that excess nitrogen you're washing out of your soil is healthy to drink?"
 

Emeraldo

Well-Known Member
Oh, Bob, you are a fountain of anti-flushing arguments! First it was: It's not what you think, then it was it is impossible as a matter of physics and/or biochemistry, then it was Ed Rosethal et al is simply wrong, then you said I was backtracking. Now it's flushing your container will cause severe environmental damage remediable only by an education program. Doesn't sound like you're continually distracting from the questions put to you? By the way, what did you mean by "backtracking"? You didn't answer, so I ask again.
 

bobrown14

Grow Journal of the Month: Dec 2017
Backtracking is when someone states something as "truthiness", then that truthiness is challenged by science and fact. The original person with the original idea, then back tracks to another view slightly different.

Think hiking in the woods and you get on the wrong trail, you turn around and go a slightly different direction but your destination is the same.

I've tried to present several different reasons why flushing is BS - take them for what they are worth.

What I'm saying here is not me coming up with a challenge its just science and knowledge being passed along to hopefully refute some crazy practice that btw is only used in the cannabis world.

I'm also suggesting that this practice along with others we like to do in the weed growing community, is not good for the environment. Specially on a larger scale. Our governments can use these practices as excuses to add controls/laws so that it could become illegal to grow your own.
Corporate farms will back that with open wallets.

Just putting that out there. There's precedent already. All you have to do is look at another cash crop - CORN and GMO corn, Monsanto, Scotts Bayer corporations. They already have politicians voting in their crap at the expense of your local small farmer and they are already in the weed biz.
 

Emeraldo

Well-Known Member
Thanks for answering the question. So "back-tracking," in your vocabulary, is something like "retreating." Ok, I get it.

Your whole point seems to be: That's not you. You don't do back-tracking. Ok, I get that, too.

However, you do appear to be an expert side-tracker. And despite your self-praise as a pseudo "soil-science" fan and would-be "educator" and now environmentalist, you have so far refused to admit that flushing has any practical benefit. For anyone. Despite overwhelming evidence to the contrary. You argue it's not only wrong, it's impossible, its a hoax, fake-news, etc. Your posts have a sheen of "micro-science" but you ignore the practical aspects. Your statements are theoretical, speculative, and consistently supported only by manipulable generalities and quotes about CEC stuff, with no real citations to authorities everyone can respect.

So no "back-tracking" there on your part.... just side-tracking like crazy. I can't reason with someone whose positions keep flitting about (even though not "back-tracking"), let alone agree with them.

Now, side-tracking is like a war of attrition. It's a strategy for "winning" an argument you would by all odds be doomed to lose: you distract, and distract, and point to something else, talk about anything but the real issue, and, above all, do not answer the direct question you've been asked. In effect, you bore your opponent to death and leave everyone else confused. So the question I have now is: What do you, Bob, gain by putting flushing down as a practice? Your posts don't seem to be about really helping or educating. More like obfuscating.

I call another witness to testify on the benefits of flushing. This time it is not Dr. Ed, or Greg Green, or Grow-Weed-Easy, all of whom are highly respected and have been consulted here as well as many others. According to Royal Queen Seeds, who are incidentally not exactly complete amateurs in the science of growing cannabis, flushing is very useful when growing in soil with chemical bottled nutrients and the grower over-uses them, i.e., gives an overdose. That is exactly what I have been telling you all along. And here's the science, according to RQS: In the overdose situation, osmosis ceases and the plant can no longer absorb water flow into the plant's cells because of the salt imbalance between soil and plant tissues, and the plant starts to look like the photos in Kokeman's opening post. The same can happen if pH is too high or too low for other reasons. By washing excess chemicals out of the soil, the grower tries to restore the salt balance so the plant can absorb water and nutrients. What Is Nutrient Lockout and How Does It Affect Cannabis?

And that, my friend, is exactly what I have been telling you about flushing all along. Go ahead and deny it, but Greg Green's words ("emergency flush") did not retract or retreat from what I said earlier but actually confirmed what I had said. Of course, the standard flushing practice is to use pH balanced water and to allow ample time for the water to disperse and dry out before continuing to feed with lower amounts of the strong chemical nutrients. (For growers like yourself, and for me for that matter, who grow in soil using organic nutrients, flushing is not really a common practice, which for me explains why you had never heard of it before when I first mentioned it.)

So, Bob, do tell: Is RQS wrong, too?

P.S. Btw where is Kokeman and what ever happened to Kokeman's plant? The more I look at those photos above, it looks to me like a case of overdose while using Miracle grow soil.
 
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bobrown14

Grow Journal of the Month: Dec 2017
I posted plenty of science written by actual scientists. Gave lots of anecdotal evidence even argued its good for the environment to not flush.

Flush away.

Enjoy.

I'll come back here 5 years from now and see how you feel about it.

RQS - dont they sell seeds?

seed vendor = soil scientist

OK - do whatever they tell you to do. They are the experts. lol
 
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