Organic soil grow - high ph problems

[mkz]

Hi

I have RQS Sweet Skunk auto plant that is 8 weeks old (4 weeks flowering)
and since week or so I have (probably) high ph caused K lockouts.

Soil is mix of rich orgainc soil (composted over a month),
some regular flower soil (ph6), some perlite and coco.
Also dolomite lime was mixed in.
Some time ago it was bit top-dressed with bit of some organic
fetilizer (smells like manure-based, 6-5-10).

I'm feeding every 2-3 days with tap water phed down by adding 2ml of
apple cider vinegar/1l to get ph close to 6, usually with some
molasses added (but lately just plain phed water).

And - it seems generous watering lowers ph to desired level,
but before next watering it gets up again.

I don't want to water more frequently (I think already bit
overwatered) - what could I do to lower ph more stabily?
For going more alkaline I'd top-dress with dolomite lime, but to
lower ph? I think some sour compost tea might help, but never tried
that. Other ideas - I have peat moss (ph4), I have blood meal, maybe
some dried manure tea?



m.

 

[Proph]

Ph rises as the medium dries.. That's normal. Your issue is most likely due to the dolomite lime. That is strong stuff and if it isn't used in the correct ratios, it will throw the ph of and you will be tryin to fix it way to often. That sounds/feels like what you are experiencing. If the soil ph is off, more than just one nutrient will be locked out. You may only be seeing signs of one right now, but others are probably close behind. Im nowhere near a chemist, lol.. And I don't mess with dolomite lime, so I'm not exactly sure how to counter act it's effects in soil.


Found this in an article on line:

Treating a high pH, caused by liming or an alkaline soil, with elemental sulfur or sulfur compounds, such as ammonium sulfate, can lower the soil pH. Elemental sulfur is changed by bacteria in the soil to sulfuric acid, which neutralizes alkalinity. Organic amendments, such as manure or peat moss also make the soil more acidic, countering soil alkalinity. However, many of these substances only have a temporary effect

 

[mkz]

I have peat moss - you think it might make sense to top dress a bit (say - cup per 3 gal pot?). Isn't manure is not the best choice for flo due to high nitrogen content?

thanks for your comments

 

[Proph]

Im not sure if top dressing with peat moss would work. You want to lower the ph of all of the soil, or at least from 6in deep on down. I don't think the peat moss will just seep into the soil like a standard top dress.. Peat absorbs water, so it will probably pull water from the soil and lead to watering more often. Most of these things need to be mixed into the soil before hand. Compost/manure would be the safest bet.. Yes manure/compost has nitrogen, but not enough to cause a nitrogen issue after a simple top dress.

 

[mkz]

Today it looks worse than yesterday (much more faint yellowing starting at veins); I think I should do something soon.
Maybe generous flush (3x pot size) and then some more with bit of fertilizer added?

 

[mkz]

Me again

@Proph - I think you are quite right. After looking up some notes
Ive found out that just before problems started I added "just in case"
bit of dolomite to water (I think my rationale was that ph was tiny
bit low, and at the very beginning I had low-ph problems also...).

Sorry I did not mention this in my first post - to be honest I completely
forgot that.

So I think this is the case. I'm wondering what to do; It's been
over two weeks since; plant is growing slowly, but looks pale and unhappy.
I'm 4th week of flowering, I think plant needs 3-4 more...

I tried to find some sulphur source, but still waiting for delivery.
For now - top dressed with manure and peat moss. Is there something I could do?

I thought of repotting - but with my skills this probably will
bring more problems than soltions . Issue is I cannot use
larger pot - it will not fit my space.

So I'm wondering is there anything I could do, but just wait and hope it will manage.
While I think it doesn't degradate that quickly anymore - I still
remove few leaves everyday.

Any other options?


Found nice article

https://extension.tennessee.edu/mtnpi/Documents/handouts/Container%20Production/pH_Adjustment_in_Containers.pdf

maybe will be useful for someone.

m

 

[Proph]

Did you end up doing the flush? That may be your best bet at this point. A slow, steady flush with RO water ph'd to 6.5 could level things out a bit.

 

[mkz]

Yes, did that, but I think its not enough yet; I think I have to wait few days let soil dry a bit before repeating...
Also thought - maybe rather than flush, it would be better just to sink pot for an hour in phed water (and readjust ph if needed?). Would be similar to flush, but should not remove that many nutrients from soil, while still neutralizing ph.

 

[mkz]

I think it is slowly recovering; today watered - runoff was more like 7 than 8 - so much better.
Top dressed with teaspoon of sulphur - we'll see.

Crossing fingers, but optimistic

thanks alot