Additives for ph control

[az2000]

He was saying his first grow went terrible because of adding lime and it locked out a bunch of nutrients because of fermitation.

Maybe he used hydrated lime (very strong and phytotoxic, but useful in an emergency if the alternative is losing the plant). Or, maybe he used dolomitic lime and had the first-grower mentality that "more is better."

I've tested the ph effect of 1 to 8 Tbsp/gal of dolomite. The first one or two have the most immediate effect, about a full point (from 5.8 to 6.. But, from 2 to 8 the ph effect was negligible, about 0.2 more for 8 Tbsp compared to 2 Tbsp. But, using that much Dolomite might provide too much Ca. I wouldn't recommend 8. Just saying that "locking out" due to excess ph adjustment, I don't see dolomitic lime doing that. Hydrated lime definitely would.

Many new growers who run into ph lockout will top-dress dolomite into the soil. That's mostly a futile exercise. It doesn't work its way into the soil like when it's amended. And, it takes two weeks for the affect on ph if it's finely powdered. If pellets, it may take months.

Dolomitic lime is widely used by non-hydro growers. It's added to most bags of grow medium by manufacturers. Growers add 1-2 Tbsp (as a rule).

It would be interesting to hear more of his reasoning. Personally, I think of healthy soil as "fermentation." Maybe you heard wrong, and he advocated oyster shell as something better to promote microbial activity. I could see passionate organic growers getting excited about oyster shell as a source of natural minerals that don't exist in dolomite (even though dolomite is organic).

 

[Nullis]

^Nice post. Micronized (very finely pulverized) lime might not exactly take two weeks to work, although the best bet is definitely adding it to the soil from the outset (if you're not using hard water). But really, all garden/ag lime (egg, oyster shell, dolomite, etc.) is chemically carbonates/carbonate minerals. There are various forms or crystal structure arrangements of calcium carbonate, called polymorphs including Calcite, Aragonite, Vaterite. Then you have other carbonate minerals such as magnesium carbonate (e.g. magnesite), with polymorphs of its own. Then you have double carbonates like dolomite which are more rare. Dolomite is a double carbonate that has an arrangement of Ca and Mg atoms which alternate in its crystal-lattice structure.

All carbonates share certain chemical properties and react in similar ways. They are not very soluble in water, they react with acids liberating CO2, they undergo thermal decomposition at high temperatures, and they can become bicarbonates (which are more soluble) by reacting with water which is saturated with CO2 (carbonic acid). The 2nd described reaction has nothing to do with our purposes, but the first and last do, and while particle size may change the rate of the reaction it will still begin immediately. For the 1st kind of reaction, the strength of the acid also influences the rate of the reaction and stronger acids will react more quickly than weak acids.

As you've seen, the effect is more pronounced at lower pH.

If it is necessary to add lime after planting to correct pH or supply calcium, it can still be done. I'd use micronized lime and try to mix it into the top layer of soil as much as possible and then water it very thoroughly, or better yet use a pump sprayer with a suitable nozzle to simulate a hard rain. If the pH of the soil is low, the acidity will react with the lime fairly instantaneously.

 

[Extacie]

I was with you guys and agree with most of what your saying except for the part about the best quality being outdoor.
Sadly i disagree.
Most of the outdoor or at least the stuff i have come across in canada has been what i would say is "ok"
Not jamaican swag bricks but no where near the sugary goodness i see from indoor.
Granted it would be stupid to argue that artificial light can come close to competing with the sun but the sun isnt a guarantee on any day.
Most places in NA have short outdoor seasons say may til oct so there really isnt much wiggle room.
Now add to that the rainy or overcast days. And the outdoor crop is really hit or miss.
I think if all the outdoor guerilla farmers could get to their crops every couple days and use the right nutes etc then we wouldnt be even having this discussion.

The use of autoflowers outside to maybe offset the other intangibles intrigues me because you could in theory pull of two outdoor harvests but i dont think the genetics are there yet.
I dont think its very practical to grow plants at the risk of going to jail for a quater zip per plant.

I think greenhouses will be the future and i cant wait.

I agree with you for the most part. Like I said earlier (or meant to say anyways) majority of the time indoor is much better quality, but the best I have ever smoked was outdoors. That has been pretty rare though & was only on 2 occasions in California from growers who had been growing 20+years. I agree I still think greenhouses are the way of the future.

I like the idea of green energy which I had never thought of, but then your overhead is still much more than it would be with greenhouses for similar quality/environments.

Using solar energy still could be a big thing of the future though, I have no idea. Sometimes driving around the state I see fields of solar panels locked up in cages.. I wonder what they are for?

 

[Extacie]

Maybe he used hydrated lime (very strong and phytotoxic, but useful in an emergency if the alternative is losing the plant). Or, maybe he used dolomitic lime and had the first-grower mentality that "more is better."

I've tested the ph effect of 1 to 8 Tbsp/gal of dolomite. The first one or two have the most immediate effect, about a full point (from 5.8 to 6.. But, from 2 to 8 the ph effect was negligible, about 0.2 more for 8 Tbsp compared to 2 Tbsp. But, using that much Dolomite might provide too much Ca. I wouldn't recommend 8. Just saying that "locking out" due to excess ph adjustment, I don't see dolomitic lime doing that. Hydrated lime definitely would.

Many new growers who run into ph lockout will top-dress dolomite into the soil. That's mostly a futile exercise. It doesn't work its way into the soil like when it's amended. And, it takes two weeks for the affect on ph if it's finely powdered. If pellets, it may take months.

Dolomitic lime is widely used by non-hydro growers. It's added to most bags of grow medium by manufacturers. Growers add 1-2 Tbsp (as a rule).

It would be interesting to hear more of his reasoning. Personally, I think of healthy soil as "fermentation." Maybe you heard wrong, and he advocated oyster shell as something better to promote microbial activity. I could see passionate organic growers getting excited about oyster shell as a source of natural minerals that don't exist in dolomite (even though dolomite is organic).

he def. seems like a passionate organic farmer, got all excited about oyster shell. He was saying it fermented his soil to the point where it killed off anything an everything living in it. I have no idea how that is or why, but that is what he said. I will have to ask him to explain more next time I see him.

 

[az2000]

For the 1st kind of reaction, the strength of the acid also influences the rate of the reaction and stronger acids will react more quickly than weak acids.

May I have your opinion on something?

I read a couple articles about feeding dissolved eggshell (calcium acetate) during transition to bloom.(<<link) What I read was not cannabis-related. I'm not sure it's wise to give extra Ca during transition. But, it did seem like a way to keep some Ca on hand to tread Ca deficiency. If Mg def, epsom salt is easily acquired. For Ca def, it seems like the only options are calcium carbonate (which takes awhile to breakdown) or calmag (which treats more than the Ca def).

Then I thought dehydrating the resulting calcium acetate to keep the powder. But, I'm not sure that's the same thing. For example, is the powder pure Ca (notwithstanding egg residue and other trace minerals in eggshell, like phosphorous)? If I put some in water will it be as readily available to the plant as when it was in its original solution?

I put 1/8 tsp in a shot glass of water. It seemed to dissolve. Took a minute and a little help with a spoon. But, I didn't see anything fall out like it was merely suspended rather than dissolved.

Sounds like you might know what's happening during dissolving, dehydrating and dehydrating.

Thanks.

 

[Extacie]

Baking soda is not good for raising pH as far as plants go. Sodium bicarbonate, too much sodium.

Oyster shell is just another form of calcium carbonate. Egg shell is calcium carbonate, too. Dolomite is calcium magnesium carbonate. Dolomitic limestone is a pulverized lime which contains some amount (6-12%) magnesium, but not as much as pure dolomite would. Dolomitic lime is popular because plants need Mg too, as do microorganisms.

All of these materials could contain traces of other minerals. Some limestone deposits have iron.

I've been growing in soil for years without pHing anything. Dolomitic lime provides Ca and Mg and helps neutralize acidity long term; mainly counteracting the acidity of the sphagnum peat in the potting mix and future acidity generated by the plant roots exchanging H+ for other nutrient cations. If you ask me, pHing soil is antithesis to growing in soil.

If you want to grow in soil, understand what goes on in soil. The soil itself and the food web it nourishes handle the nuances of pH.
There are so many misconceptions about pH. pH isn't all there is to nutrient availability and especially not in soil. Different nutrients are more/less soluble in water/plant available depending on pH. There is no exact, 'perfect' pH at which everything is just fine and beyond that biological activity in the soil is influencing the pH all the time. However, soil itself was designed to resist sudden pH changes. Quality soil and particularly earthworm castings, humus and compost have Cation Exchange and buffering capacity in their own right. They also contain humic substances, natural chelating compounds which increase nutrient availability.

CEC is very important to soil and what makes soil such a great medium to grow in. Soil has sustained life for hundreds of thousands of years, and whole forests of huge trees without anybody giving it pH up or anything really. Now, if you understand cation exchange and base saturation you will see why people use dolomitic or garden lime in agricultural plots in certain areas and in potting mix.
Besides K, Ca and Mg are the most exchangeable base cations, and with low BS% pH generally falls. Potting mix has other considerations since it generally contains sphagnum peat moss which is acidic. Even if it came limed chances are it could use more from the start to prevent the accumulation of reserve acidity. Garden/dolo lime (carbonates) aren't very soluble in water; so it mainly dissolves over some period of time depending on particle size. There is some in soil as precipitate, acidity dissolves it gradually and the Ca, Mg cations are either taken up by the plant or adsorbed to soil colloids (preventing exchangeable H+). With this and microbial activity working as it should there is truly no need to pH anything.



Lots of new growers like to blame their fuckups on products they used, it is interesting. Who knows what else could have gone wrong their. Although lime is difficult to over-do, there are instances in which it should not be used, or less should be used. Never use hydrated or slaked lime as they are much harsher. Probably no need to use lime if your water source is alkaline and has minerals dissolved in it already.

Great post! Thank you for taking the time to reply.


One more note on greenhouses vs outdoor vs indoor I would like to add:

@Mr. Schroederific,
Have you ever grown outdoors under the sun?

This was my first year doing so, but I learned that plants grow MUCH faster & larger with bigger yields under the sun provided they have lots of good soil to grow into. I made a lot of mistakes throughout this grow but just harvested a couple the other day and they litterally had stalks like tree trunks, I had to cut them with a saw, the 32" lopper just wouldn't do/fit around the stalk. Amazing to watch them grow under the soon, completely different than growing under lights

 

[Nullis]

May I have your opinion on something?

I read a couple articles about feeding dissolved eggshell (calcium acetate) during transition to bloom.(<<link) What I read was not cannabis-related. I'm not sure it's wise to give extra Ca during transition. But, it did seem like a way to keep some Ca on hand to tread Ca deficiency. If Mg def, epsom salt is easily acquired. For Ca def, it seems like the only options are calcium carbonate (which takes awhile to breakdown) or calmag (which treats more than the Ca def).

Then I thought dehydrating the resulting calcium acetate to keep the powder. But, I'm not sure that's the same thing. For example, is the powder pure Ca (notwithstanding egg residue and other trace minerals in eggshell, like phosphorous)? If I put some in water will it be as readily available to the plant as when it was in its original solution?

I put 1/8 tsp in a shot glass of water. It seemed to dissolve. Took a minute and a little help with a spoon. But, I didn't see anything fall out like it was merely suspended rather than dissolved.

Sounds like you might know what's happening during dissolving, dehydrating and dehydrating.

Thanks.

When you dissolve a substance\salt in water, if the substance is water soluble like calcium acetate is, the ions dissociate into the solution. Calcium carbonate, being only sparingly soluble in water wont do this so readily and most of the CaCO3 will be in water as precipitate. At lower pH CaCO3 will begin to dissolve and under attack by an acid like acetic acid other products will form, like calcium acetate. Calcium bicarbonate is also likely to form at least temporarily, but would simply revert back to calcium carbonate if present upon drying.

Calcium acetate will form and remain as a white solid. You should see crystals of calcium acetate form even by soaking carbonate rocks in vinegar.

General Organics CaMg essentially is the result of dissolving oyster shell and dolomite in vinegar, although they've perfected the process of course and there should be plant extracts in there as well.