Soil buffer and pH adjustments

[lilnug420]

i grow outdoors

i have a question about how soil buffers work, so i've been growing for a few years using terra canna professional which has a ph of around 5.8

i was told that soils have buffers that make it so the ph always stays the same, if that's so, what's the point of adjusting ph before watering? if the soil adjusts itself?


how long do these buffers last? do they get used up with time?


does flushing a plant use up the buffer? i wanna do a flush before up-potting my girls to get rid of excess salts, when i flush i usually run tap water trough the soil for half an hour or so, until the water comes out clear and not yellow


would this consume the ph buffer? i wanna flush before uppotting from a 3gal container to a 10 gal one, and then do another flush a week or so before they switch to flowering.

 

[SmokingWings]

A lot of good and very interesting questions. I get the feeling that most of the questions and the answers will apply to natural or mineral soils.

i've been growing for a few years using terra canna professional

Sounds like the Terra Professional Plus which is peat moss and enough lime to bring the pH of the mix up to 5.8 to 6.3 for the user. The company adds a bit of wood bark and some natural fertilizers. I could not find a more complete listing of what they put in the mix other than a lot of peat and lime. It might be on the back of the bag but it is not showing up on-line.

I am not sure that the usual info on buffering as it applies to natural soil mixes would apply considering all the peat moss but no mention of mineral soils or compost added into the mix.

Are you also using the Terra Canna line of liquid fertilizers?

 

[Phytoplankton]

i grow outdoors

i have a question about how soil buffers work, so i've been growing for a few years using terra canna professional which has a ph of around 5.8

i was told that soils have buffers that make it so the ph always stays the same, if that's so, what's the point of adjusting ph before watering? if the soil adjusts itself?
run tap water trough the soil for half an hour or so, until the water comes out clear and not yellow
week or so before they switch to flowering.

Welcome to the forum, good questions, I'll try to answer what I can. First it apears terra canna is a soiless media, it's peat based, hence the lower PH. I couldn't find where they say whether its buffered or not, but for a peat mix to have a PH of 5.8 it almost has to be. Most potting soils have a ph of around 6-7, buffered means that something (usually dolomite or lime) is added to increase/stabilize the PH as the water infiltrates through the media, which is why you PH your input. Dolomite breaks down very slowly making it a good long term buffering agent. Would it be possible to wash it out, probably to some extent, but I don't know for certain. In soil you want to adjust you nute/water PH to around 6.2, nutrients are more available and more easily absorbed by the plant at different PH's, so as the water first hits the roots they will absorb those nutrients available at that lower PH, as the water/nutes infiltrate through the soil and it buffers to a higher PH, the roots will absorb those nutrients available at the higher PH range. All that said, soiless grows have different parameters than soil grows (and I'm a soil guy).

 

[Emilya Green]

i grow outdoors

i have a question about how soil buffers work, so i've been growing for a few years using terra canna professional which has a ph of around 5.8

i was told that soils have buffers that make it so the ph always stays the same, if that's so, what's the point of adjusting ph before watering? if the soil adjusts itself?


how long do these buffers last? do they get used up with time?


does flushing a plant use up the buffer? i wanna do a flush before up-potting my girls to get rid of excess salts, when i flush i usually run tap water trough the soil for half an hour or so, until the water comes out clear and not yellow


would this consume the ph buffer? i wanna flush before uppotting from a 3gal container to a 10 gal one, and then do another flush a week or so before they switch to flowering.

There is a lot of confusion out here about soil and how it is supposed to work. Every time I do this it starts an argument, but let me explain how soil was described to me, and why it is designed the way it is at the manufacturer.

First buffers. Buffers are not there to keep the soil at a certain pH. Within limits, we really don't care what the soil's pH is, but designers of soil have built in a tool that lets you work with common synthetic nutrients with ease. There are buffers in the soil that can be at both the upper and lower ends of the usable pH scale. Lower end buffers are mostly used in hydro situations where the working pH is 5.1-5.9 and are designed to pull the pH up from the lower end to around 5.9 pH. The goal is to adjust your fluid to 5.5 and then let the buffers and the nutes being used up, slowly drift the pH of the medium up to the high end, sweeping through the entire pH range as it happens. There is an advantage gained by sweeping through the entire range since some elements are more able to get up into the plant at different pH levels.

Soil is usually buffered to the high end of the usable pH range in soil, 6.2-6.8 pH. The intent of this is to allow the gardener to adjust the incoming fluids to 6.3, and then the buffers will slowly drift the pH up to the high end, again drifting through the entire working pH range. Your buffers allow the nutrients to break free of their bonds that keep them stable in the bottle, and then be available to the plant for the maximum amount of time.

Soil has been used like this for at least 100 years. Farmers will add dolomite lime to "sweeten" the soil (or raise its base pH) and it has been commonly known all these years that in a closed container grow, it was best to come in at the low end and let the soil do its thing to drift your nutrients through the entire range. Soil used in this way is a tool, one that has been intentionally built into soil since commercial soils began to be manufactured.

Don't let anyone tell you that soil pH needs to be adjusted down from where the factory put it, or that you even need to run pH tests on your soil. Almost every soil out there is pH buffered to 6.8 for a reason. This nonsense that you never have to adjust the pH of your fluids if you get your soil right is simply a fad, carried on by a few online personalities in the last 5 years or so. While this newfangled method might work, the age old advice is to always pH adjust your incoming fluids to 6.3, the point where the most nutes are the most available to the plant, and then let the soil do the job it was designed to do.

This advice however is only for someone using common EDTA chelated synthetic nutes, that are designed to free themselves of their chelation only within that working 6.2-6.8 pH range. If you are growing organically, or with amino acid chelated nutes, pH doesn't matter much and wherever your soil happens to be should be fine.

Yes, flushing will dissolve some of the dolomite lime, and your buffering will reduce a tiny bit. This is no crisis, at least in a normal flush. What you are doing is excessive. To clear soil of salts we know that it takes about 3x the volume of the container to do so. Running the hose for a half hour is overkill and I would advise against it.

 

[SmokingWings]

There is a lot of confusion out here about soil and how it is supposed to work. Every time I do this it starts an argument, but let me explain how soil was described to me, and why it is designed the way it is at the manufacturer.

First buffers. Buffers are not there to keep the soil at a certain pH. Within limits, we really don't care what the soil's pH is, but designers of soil have built in a tool that lets you work with common synthetic nutrients with ease. There are buffers in the soil that can be at both the upper and lower ends of the usable pH scale. Lower end buffers are mostly used in hydro situations where the working pH is 5.1-5.9 and are designed to pull the pH up from the lower end to around 5.9 pH. The goal is to adjust your fluid to 5.5 and then let the buffers and the nutes being used up, slowly drift the pH of the medium up to the high end, sweeping through the entire pH range as it happens. There is an advantage gained by sweeping through the entire range since some elements are more able to get up into the plant at different pH levels.

Soil is usually buffered to the high end of the usable pH range in soil, 6.2-6.8 pH. The intent of this is to allow the gardener to adjust the incoming fluids to 6.3, and then the buffers will slowly drift the pH up to the high end, again drifting through the entire working pH range. Your buffers allow the nutrients to break free of their bonds that keep them stable in the bottle, and then be available to the plant for the maximum amount of time.

Soil has been used like this for at least 100 years. Farmers will add dolomite lime to "sweeten" the soil (or raise its base pH) and it has been commonly known all these years that in a closed container grow, it was best to come in at the low end and let the soil do its thing to drift your nutrients through the entire range. Soil used in this way is a tool, one that has been intentionally built into soil since commercial soils began to be manufactured.

Don't let anyone tell you that soil pH needs to be adjusted down from where the factory put it, or that you even need to run pH tests on your soil. Almost every soil out there is pH buffered to 6.8 for a reason. This nonsense that you never have to adjust the pH of your fluids if you get your soil right is simply a fad, carried on by a few online personalities in the last 5 years or so. While this newfangled method might work, the age old advice is to always pH adjust your incoming fluids to 6.3, the point where the most nutes are the most available to the plant, and then let the soil do the job it was designed to do.

This advice however is only for someone using common EDTA chelated synthetic nutes, that are designed to free themselves of their chelation only within that working 6.2-6.8 pH range. If you are growing organically, or with amino acid chelated nutes, pH doesn't matter much and wherever your soil happens to be should be fine.

Yes, flushing will dissolve some of the dolomite lime, and your buffering will reduce a tiny bit. This is no crisis, at least in a normal flush. What you are doing is excessive. To clear soil of salts we know that it takes about 3x the volume of the container to do so. Running the hose for a half hour is overkill and I would advise against it.

Does this apply when the plant is growing in a peat moss and lime mixture?

There is no mention, or at least easy to find mention, of any mineral soils, composts or earthworm castings being added to the Terra Canna Professional Plus mix. Some mention of adding nutrients but not which ones, how much or how long they will be able to help the plants

 

[Emilya Green]

Does this apply when the plant is growing in a peat moss and lime mixture?

There is no mention, or at least easy to find mention, of any mineral soils, composts or earthworm castings being added to the Terra Canna Professional Plus mix. Some mention of adding nutrients but not which ones, how much or how long they will be able to help the plants

That sounds like it would work as a soilless / hydro nute situation by coming in low and letting the liquid slowly rise in pH as it interacts with the peat and lime and some of the acidic nutes get used up.

 

[lilnug420]

A lot of good and very interesting questions. I get the feeling that most of the questions and the answers will apply to natural or mineral soils.


Sounds like the Terra Professional Plus which is peat moss and enough lime to bring the pH of the mix up to 5.8 to 6.3 for the user. The company adds a bit of wood bark and some natural fertilizers. I could not find a more complete listing of what they put in the mix other than a lot of peat and lime. It might be on the back of the bag but it is not showing up on-line.

I am not sure that the usual info on buffering as it applies to natural soil mixes would apply considering all the peat moss but no mention of mineral soils or compost added into the mix.

Are you also using the Terra Canna line of liquid fertilizers?

i'm using megacrop as fertilizer

 

[lilnug420]

There is a lot of confusion out here about soil and how it is supposed to work. Every time I do this it starts an argument, but let me explain how soil was described to me, and why it is designed the way it is at the manufacturer.

First buffers. Buffers are not there to keep the soil at a certain pH. Within limits, we really don't care what the soil's pH is, but designers of soil have built in a tool that lets you work with common synthetic nutrients with ease. There are buffers in the soil that can be at both the upper and lower ends of the usable pH scale. Lower end buffers are mostly used in hydro situations where the working pH is 5.1-5.9 and are designed to pull the pH up from the lower end to around 5.9 pH. The goal is to adjust your fluid to 5.5 and then let the buffers and the nutes being used up, slowly drift the pH of the medium up to the high end, sweeping through the entire pH range as it happens. There is an advantage gained by sweeping through the entire range since some elements are more able to get up into the plant at different pH levels.

Soil is usually buffered to the high end of the usable pH range in soil, 6.2-6.8 pH. The intent of this is to allow the gardener to adjust the incoming fluids to 6.3, and then the buffers will slowly drift the pH up to the high end, again drifting through the entire working pH range. Your buffers allow the nutrients to break free of their bonds that keep them stable in the bottle, and then be available to the plant for the maximum amount of time.

Soil has been used like this for at least 100 years. Farmers will add dolomite lime to "sweeten" the soil (or raise its base pH) and it has been commonly known all these years that in a closed container grow, it was best to come in at the low end and let the soil do its thing to drift your nutrients through the entire range. Soil used in this way is a tool, one that has been intentionally built into soil since commercial soils began to be manufactured.

Don't let anyone tell you that soil pH needs to be adjusted down from where the factory put it, or that you even need to run pH tests on your soil. Almost every soil out there is pH buffered to 6.8 for a reason. This nonsense that you never have to adjust the pH of your fluids if you get your soil right is simply a fad, carried on by a few online personalities in the last 5 years or so. While this newfangled method might work, the age old advice is to always pH adjust your incoming fluids to 6.3, the point where the most nutes are the most available to the plant, and then let the soil do the job it was designed to do.

This advice however is only for someone using common EDTA chelated synthetic nutes, that are designed to free themselves of their chelation only within that working 6.2-6.8 pH range. If you are growing organically, or with amino acid chelated nutes, pH doesn't matter much and wherever your soil happens to be should be fine.

Yes, flushing will dissolve some of the dolomite lime, and your buffering will reduce a tiny bit. This is no crisis, at least in a normal flush. What you are doing is excessive. To clear soil of salts we know that it takes about 3x the volume of the container to do so. Running the hose for a half hour is overkill and I would advise against it.

i'm pretty sure terra canna professional is around 5.8 to 6.3ph


would that mean it would be best to water at 5.5ph? and it will slowly drift up to 6.3 as the soil dries?

i use ph drops to measure ph as i've stopped used ph meters as i find them a real pain in the bum, this also means my measurement is not gonna be very precise with drops

 

[Emilya Green]

i'm pretty sure terra canna professional is around 5.8 to 6.3ph


would that mean it would be best to water at 5.5ph? and it will slowly drift up to 6.3 as the soil dries?

i use ph drops to measure ph as i've stopped used ph meters as i find them a real pain in the bum, this also means my measurement is not gonna be very precise with drops

first, its not soil... so it should be run in the hydro range of 5.5-6.1 and with hydro nutes. So yes, water at 5.5 or so, and let it drift upwards to 6.1.... 6.3 is out of range.

 

[lilnug420]

first, its not soil... so it should be run in the hydro range of 5.5-6.1 and with hydro nutes. So yes, water at 5.5 or so, and let it drift upwards to 6.1.... 6.3 is out of range.

ok thanks! about flushing, you said x3 size of container, so if my pot is 11 liters, i need to water 33 liters correct?

 

[Emilya Green]

ok thanks! about flushing, you said x3 size of container, so if my pot is 11 liters, i need to water 33 liters correct?

That is correct

 

[lilnug420]

first, its not soil... so it should be run in the hydro range of 5.5-6.1 and with hydro nutes. So yes, water at 5.5 or so, and let it drift upwards to 6.1.... 6.3 is out of range.

one more thing, i saw this chart online:


considering i'm using ph drops to measure, so i'm never going to be very accurate, (i have 2 cheap ph meters, but i don't trust them too much, and i cant afford the professional stuff, and even if i did, i'm too clumsy and would probably drop it a month after owning it)

would it be ok if one time i water at around 5/5.5 ph and the other closer to 6/6.5ph?

so i would go through all the ph ranges where the nutrients are available? (since ph drops aren't that accurate, this way i would be sure to be getting all the nutrients)

 

[seaofgreen18]

i grow outdoors

i have a question about how soil buffers work, so i've been growing for a few years using terra canna professional which has a ph of around 5.8

i was told that soils have buffers that make it so the ph always stays the same, if that's so, what's the point of adjusting ph before watering? if the soil adjusts itself?


how long do these buffers last? do they get used up with time?


does flushing a plant use up the buffer? i wanna do a flush before up-potting my girls to get rid of excess salts, when i flush i usually run tap water trough the soil for half an hour or so, until the water comes out clear and not yellow


would this consume the ph buffer? i wanna flush before uppotting from a 3gal container to a 10 gal one, and then do another flush a week or so before they switch to flowering.

You need one of these 6.8-7.0 soil pH AG lime to bring it up sulfur to Lower it the pH depends on your inputs and tge the water pH is important as well I use citric acid to lower and baking soda to raise water pH with the same meter give it a shot stable pH is important!

 

[Emilya Green]

one more thing, i saw this chart online:


considering i'm using ph drops to measure, so i'm never going to be very accurate, (i have 2 cheap ph meters, but i don't trust them too much, and i cant afford the professional stuff, and even if i did, i'm too clumsy and would probably drop it a month after owning it)

would it be ok if one time i water at around 5/5.5 ph and the other closer to 6/6.5ph?

so i would go through all the ph ranges where the nutrients are available? (since ph drops aren't that accurate, this way i would be sure to be getting all the nutrients)

it is much better to be accurate. 6.3 every time in soil, and 5.8 in soiless, for the best nutrient response

 

[Wastei]

first, its not soil... so it should be run in the hydro range of 5.5-6.1 and with hydro nutes. So yes, water at 5.5 or so, and let it drift upwards to 6.1.... 6.3 is out of range.

Terra Canna is peat based and should optimally be run at pH 6-6.5 IMO. If lime and other buffering agent are not mainly added to offset peat and other mediums natural acidity (pH 3.5-4.5) what do you mean they're mainly added for? The obvious is to add Ca and Mg, but other than that?

Terra Canna is amended with lime that will keep pH somewhere around 6-7 in the medium without pH adjustments before its been used up by the plant.

 

[lilnug420]

Terra Canna is peat based and should optimally be run at pH 6-6.5 IMO. If lime and other buffering agent are not mainly added to offset peat and other mediums natural acidity (pH 3.5-4.5) what do you mean they're mainly added for? The obvious is to add Ca and Mg, but other than that?

Terra Canna is amended with lime that will keep pH somewhere around 6-7 in the medium without pH adjustments before its been used up by the plant.

do you recon ph drops are precise enough for an amateur grower? like i said i can't really afford the expensive meters, and even if i did i'd break em so i'd rather not. i have 2 cheap meters but i was told they're bad

 

[Phytoplankton]

The drops will get you in the ballpark (close enough). The issue with cheap meters is they need to be calibrated often, which is a PITA.

 

[SmokingWings]

do you recon ph drops are precise enough for an amateur grower?

considering i'm using ph drops to measure, so i'm never going to be very accurate, (i have 2 cheap ph meters, but i don't trust them too much,

this also means my measurement is not gonna be very precise with drops

I understand where you are coming from but in the long run you will find out that the pH test kits using the drops are accurate. You might be talking yourself out of believing that the drops kit is giving you an accurate reading.

The pH meters, whether digital or analog, make testing quicker but not necessarily more or less accurate.

i have 2 cheap meters but i was told they're bad

The old saying of "you get what you paid for" is probably applying to the situation.

 

[Wastei]

I understand where you are coming from but in the long run you will find out that the pH test kits using the drops are accurate. You might be talking yourself out of believing that the drops kit is giving you an accurate reading.

The pH meters, whether digital or analog, make testing quicker but not necessarily more or less accurate.


The old saying of "you get what you paid for" is probably applying to the situation.

I've had cheap meters last me years. I believe it's more important how you store and keep them. They usually die on me whenever I have a couple of years of hiatus from growing. It does'nt matter the brand, if they go dry they die. I believe some guy on another forum revived his by letting it sit in vinegar for a couple of days. Cheers!

 

[Wastei]

do you recon ph drops are precise enough for an amateur grower? like i said i can't really afford the expensive meters, and even if i did i'd break em so i'd rather not. i have 2 cheap meters but i was told they're bad

do you recon ph drops are precise enough for an amateur grower? like i said i can't really afford the expensive meters, and even if i did i'd break em so i'd rather not. i have 2 cheap meters but i was told they're bad

In peat mixes you'll be fine. Runoff pH should optimally be somewhere around pH 5.7-6.5, its better to be slighly higher in pH than lower in containers. I used drops for years before getting a pH pen and I still have litmus paper as a backup if my meters ever would break on me. Cheers!