Soil very acidic near stalk but normal everywhere else.

[Usernsme423]

The soil in this pot is very acidic around the rootball/stalk area, like a 4 on the scale, but the soil on the outside of the pot is all testing within normal ranges. My plants seem to be showing signs of nutrient burn and/or lockout. I believe I overfed my plants with liquid nutrients that eventually threw off my soil pH and is now causing some kind of lock out issues. When I check the area next to the stalk it’s comes back very acidic but when I test the outer edges it comes back within completely normal range.

Has anyone experienced something like this? How should I go about fixing this? My plan is to top dress Dolomite Lime around the stalk. I was also thinking about baking soda because it supposably works faster.

The plants are about 2-4 weeks into flower.

Any information or personal experiences is much appreciated.

 

[flylowgethigh]

If you are using a single probe pH meter, congratulations! Your soil is sparking. Go look at my 3rd grow diary for my spark reading when I went into the 10 gallon bags.

I have no scientific proof, and neither soil company I use has a clue what this is, but in my hillbilly way of thinking the probe is reading a galvanic kind of thing with ions and cations going off.

Here... this soil pH's at over 7 in the soil tub, without roots working.:

https://www.icmag.com/forum/marijuan...3#post17917183

That post was made when the plants were dropped to a 12/12 light cycle. Look at how the plants have grown in that sparking soil since. Keep yours nice and moist, and I water with pH 6.3. If you over fed the soil, try to wash through it with enough water. My early attempts were stymied by not having the soil wet enough. A SWICK system solved that.

 

[troutman]

Don't use baking soda. Use regular limestone or pH up.

pH below 5.5 will cause deficiencies.

 

[Creeperpark]

Topdressing with lime can turn around and bite you on the ass. You can add just a tiny pinch of lime to some RO or Rain and bubble it for a while and slowly buffer the pH. Just about 129 ppm in the water will buffer your plant's pH.

 

[Switcher56]

Lime for acidity?

 

[HempKat]

Lime for acidity?

Yeah, think of it as alkalime

 

[HempKat]

Usually the suggestion on testing ph is to measure the run off rather then multiple specific points in the soil. The idea being this gives you the best average ph of what your roots are seeing. If you had a large area of 4.0 ph then pretty much all nutrients would be locked out and you would see multiple wide spread deficiency issues. Since you didn't include pics and you kind of downplayed what you suspect are deficiency issues I'm going to make a guess that you will come back with a slightly acidic ph when you measure the run off, enough to cause a little deficiency but not what you should be seeing if you had wide spread acidity as bad as what you're reading near the stalk. So maybe it will come back like 6.0 or 5.8 maybe even 5.5. Whatever the run off reads you would then just try to raise the ph on it before you feed the plants, enough that you think it would bring the run off up to around 6.5 ph. Since you think there is some lockout happening but you won't be able to know how much to adjust it until you feed the plant measure the ph of the water/nutrient mix before you add it to the soil and if it's showing slightly acidic there then bring the ph up to 6.5 before adding it to the soil and then test the runoff. If it's reading around 6.5 before adding then maybe bring it up to 6.8 then add and measure the runoff. Then just keep adjusting it each feeding until you find what it needs to be to get your runoff in range.

The main nutrients you need in flower are potassium and phosphorous and both those are good up to a ph of 7.0 above 6.5 to 7.0 all you really lose (lockout) is manganese and iron. Below 6.5 down to 6.0 on the other hand you lose (lockout) Phosphorous, Calcium and Magnesium but at that level you'll still have , Nitrogen, Potassium, Manganese, Iron and Boron. From 6.0 down to 5.0 you lockout everything except Manganese, Iron and Boron. Below 5.0 tto 4.0 all you have available is iron and when you hit 4.0 and lower you lock out everything. I'll attach a graph that gives you a visual of how the various ph levels impact the more common nutrients such as the ones I've mentioned here. Since you're in flower the most critical lose to avoid is the Phosphorous since that's the main driver for flower development, potassium is important to but like I indicated above potassium hangs in there pretty good even when you're out of the ideal range of 6.5. Calcium, and magnesium are important too but more for overall plant health then for flower development. If you had described what you suspect are signs of lockout I might be able to make a better guess as to what your overall ph is and what is being locked out. I suspect your overall ph is like I said above, somewhere around 6.0 which would have phosphorous, calcium and magnesium locked out. Phospherous probably won't show too much yet other then slow flower development because you're early in flower. If I'm right then your signs should be something along the lines of older leaves yellowing from the center vein outwards, maybe even the older leaves turning purple or bronzish also the petioles might be turning red possibly collapsing, new shoots might be withered or dead and leaves both young and old might show tip burn. Probably the most serious sign would be stunted growth of the plant which during this stage should be in the stretch phase. If you are seeing all that plus other signs then your ph is probably even lower then I suspect. I'll also post a graphic I have that describes some of the more common signs of various deficiencies.

 

[Creeperpark]

You have to be very careful using lime because it must be composted into your soil before living roots can be in that soil. It takes a minimum of 30 days to compost it in a good soil mix.

 

[Subu]

Dolomite Lime.

 

[exploziv]

You have to be very careful using lime because it must be composted into your soil before living roots can be in that soil. It takes a minimum of 30 days to compost it in a good soil mix.

Any ideea on how to dose it? I am using dolomite lime, but they give application rates just by the hectare. I did calculate how much I need by soil surface, but I am guessing that might be off, since I figured it myself based on large scale aplication rate.

 

[Switcher56]

Dolomite Lime.

Thanks I had a major brain fart LOL

 

[flylowgethigh]

You're better off if you just listen to what I wrote. If the soil outside the root zone is normal pH, and it is sparking in the root zone, better get some more water in there and expand the roots.

I also use Rootwise microbes and enzymes.

Add lime and you will snatch defeat from the jaws of victory IMO.

But it's your grow, and I am just some random voice on the internet with data and results.

 

[hyposomniac]

First, what do you mean by "soil", Amended peat or actual soil?
​​​​​You can usually just rinse out the soluble salts you poured in there, then start watering more thoroughly with run off every time.

 

[Creeperpark]

For rainwater, distilled water, or reverse osmosis filtered water. Using an airstone you can bubble some dolomite lime (like 1/8[SUP]th[/SUP] teaspoon per gallon of water) for 24 hours. You would have water about 60 PPM at 7.0 pH that will help buffer the soil. Use the water every time you water and monitor your pH.

 

[HempKat]

Any ideea on how to dose it? I am using dolomite lime, but they give application rates just by the hectare. I did calculate how much I need by soil surface, but I am guessing that might be off, since I figured it myself based on large scale aplication rate.

I may be wrong because it's been a while since I did any growing but if memory serves me correctly I added dolomite lime at a rate of about 2 tablespoons per gallon of soil with no negative results.

 

[exploziv]

Cool, man, thanks. Thst is exactly what I been told for some other guy and right around what i calculated from the big scale application chart. So it must be true..

 

[flylowgethigh]

I wonder if he screwed up the soil with a bunch of pH up or baking soda. The spark thing is real folks, embrace it. I'll take a pic of the reading on soil I am recycling now, which is cooking in prep for the next run. I try to get it over 7.0 with no vegitation, and it will spark down below 4 when things are rocking.

 

[Creeperpark]

Repeat
You have to be very careful using lime because it must be composted into your soil before living roots can be in that soil. It takes a minimum of 30 days to compost it in a good soil mix.