Recycled amended soil high in ph/ppm

StalkerAF · Jul 12, 2025

Hello all.

I am testing out recycling my organic soil from the last grow and added an assortment from down to earth amendments gathered from a recipe I found from 420 scene on you tube. I test and learn a lot from him.

Question :

The current soil ph level is 7.5+ which looks like I can add elemental sulfur to easily fix this. I have not replanted with this soil yet and it’s in a compost bin.

When I check the ppm level of the soil from a slurry mix, it’s maxed over 3000ppm. Should I be concerned about this? How would I control this other than flushing because the soil is in a compost bin currently.

Not in a rush to transplant because I’m in the middle of mainlining the next lady so there’s some time to play around with the recycled soil.

Thanks a lot for any advice!

mancorn · Jul 12, 2025

StalkerAF said:
When I check the ppm level of the soil from a slurry mix, it’s maxed over 3000ppm. Should I be concerned about this?

No. PPM is not really relevant in organic soil. PPM measures synthetic fertilizers (soluble salts nutrients) dissolved in the water. In organic soil, the majority of nutrients are not immediately soluble, but bound within the organic matter or adsorbed in soil particles. But active microbial can still jack up your PPM readings.

Best to get your soil tested and you’ll actually know what the nutrient levels are. Only cost you ~$20 at UMass.

Soil and Plant Nutrient Testing Laboratory : Soil and Plant Nutrient Testing Laboratory Services : Center for Agriculture, Food, and the Environment (CAFE) at UMass Amherst

Why Test Soil?Here are five good reasons!Nutrient levels - Test results provide you with soil nutrient levels and fertilizer recommendations when needed.Soil Acidity - Soil pH and exchangeable acidity are measured for the determination of lime requirements.Environmental Protection - Test results...

www.umass.edu

JIMKSI64 · Jul 12, 2025

mancorn said:
No. PPM is not really relevant in organic soil. PPM measures synthetic fertilizers (soluble salts nutrients) dissolved in the water. In organic soil, the majority of nutrients are not immediately soluble, but bound within the organic matter or adsorbed in soil particles. But active microbial can still jack up your PPM readings.

Best to get your soil tested and you’ll actually know what the nutrient levels are. Only cost you ~$20 at UMass.

Soil and Plant Nutrient Testing Laboratory : Soil and Plant Nutrient Testing Laboratory Services : Center for Agriculture, Food, and the Environment (CAFE) at UMass Amherst

Why Test Soil?Here are five good reasons!Nutrient levels - Test results provide you with soil nutrient levels and fertilizer recommendations when needed.Soil Acidity - Soil pH and exchangeable acidity are measured for the determination of lime requirements.Environmental Protection - Test results...

www.umass.edu

I read that statement of EC/ppm meaning nothing a year ago when I started so I measured my fish poop flower nutes at pH adjusted to 6.3.
Yes that number is not real. It would have smoked a grow in hours if it was.......

Eledin · Jul 12, 2025

Wont all the nitrogen from the old roots be a problem? I always heard that and I think I got N toxicity once for using too much reused soil, but not sure so I only reuse the outter layer and I mix 30/70 old-new. I cant compost it thats part of the reason, but the nitrogen is not going anywhere even if you compost the soil right? It will just be readily available. If anyone has the answer to this id like to know because if I can recycle all my soil then thats huge, I like to be eco-friendly and spend less money while doing so hahaha.

StalkerAF · Jul 12, 2025

mancorn said:
No. PPM is not really relevant in organic soil. PPM measures synthetic fertilizers (soluble salts nutrients) dissolved in the water. In organic soil, the majority of nutrients are not immediately soluble, but bound within the organic matter or adsorbed in soil particles. But active microbial can still jack up your PPM readings.

Best to get your soil tested and you’ll actually know what the nutrient levels are. Only cost you ~$20 at UMass.

Soil and Plant Nutrient Testing Laboratory : Soil and Plant Nutrient Testing Laboratory Services : Center for Agriculture, Food, and the Environment (CAFE) at UMass Amherst

Why Test Soil?Here are five good reasons!Nutrient levels - Test results provide you with soil nutrient levels and fertilizer recommendations when needed.Soil Acidity - Soil pH and exchangeable acidity are measured for the determination of lime requirements.Environmental Protection - Test results...

www.umass.edu

JIMKSI64 · Jul 12, 2025

I am in the research mode over rehabilitating fox farms soil. Going to look at buying bags vrs all the stuff needed to restore the soil to production and I have also decided that if the cost savings is not worth it than seeing about sterilizing the soil and using chemical nutes like Jacks.
This current and my next should give me 10 5 gallon pots worth of FF soils to use for the test. When researching I found a lot of wrong in these recipes as I have amended soil in the ground to grow food and the products used are the same.

RGWD0202 · Jul 12, 2025

StalkerAF said:
Hello all.

I am testing out recycling my organic soil from the last grow and added an assortment from down to earth amendments gathered from a recipe I found from 420 scene on you tube. I test and learn a lot from him.

Question :

The current soil ph level is 7.5+ which looks like I can add elemental sulfur to easily fix this. I have not replanted with this soil yet and it’s in a compost bin.

When I check the ppm level of the soil from a slurry mix, it’s maxed over 3000ppm. Should I be concerned about this? How would I control this other than flushing because the soil is in a compost bin currently.

Not in a rush to transplant because I’m in the middle of mainlining the next lady so there’s some time to play around with the recycled soil.

Thanks a lot for any advice!

Definitely can reuse your old soil, make sure you get it hydrated before using or it’ll become hydrophobic and watering will be a bitch if it isn’t moistened properly first. Double check me on this but I believe lime will lower your soil ph, but I don’t think you want to use dolomite. Could probably water in lower ph’d water maybe around 6 or so and see if that helps. Also add some gypsum to your soil if you haven’t yet.

Eledin · Jul 12, 2025

I add all sorts of ammendments and my trick for not having to play around PH things is really simple, worm castings. If I had to calculate the PH with all the things I add it would be a nightmare. Dolomitic lime is also a good addition, I use it instead of bone meal for the calcium and magnessium, it will rise your PH only if its too low.

StalkerAF · Jul 12, 2025

This is great info thank you sharing.

I only have about 10 gallons of dirt I’m recycling so very small scale. As much as I have sent on the indoor setup what’s another $20…

Good to know about the ppm in the soil when growing organically. I will address the high ph level first.

StalkerAF · Jul 12, 2025

Eledin said:
Wont all the nitrogen from the old roots be a problem? I always heard that and I think I got N toxicity once for using too much reused soil, but not sure so I only reuse the outter layer and I mix 30/70 old-new. I cant compost it thats part of the reason, but the nitrogen is not going anywhere even if you compost the soil right? It will just be readily available. If anyone has the answer to this id like to know because if I can recycle all my soil then thats huge, I like to be eco-friendly and spend less money while doing so hahaha.

Good to know, I’ll research this.

StalkerAF · Jul 12, 2025

RGWD0202 said:
Definitely can reuse your old soil, make sure you get it hydrated before using or it’ll become hydrophobic and watering will be a bitch if it isn’t moistened properly first. Double check me on this but I believe lime will lower your soil ph, but I don’t think you want to use dolomite. Could probably water in lower ph’d water maybe around 6 or so and see if that helps. Also add some gypsum to your soil if you haven’t yet.

The little I understand about adjusting soil ph levels is sulfur will decrease and line can raise.

StalkerAF · Jul 12, 2025

JIMKSI64 said:
I read that statement of EC/ppm meaning nothing a year ago when I started so I measured my fish poop flower nutes at pH adjusted to 6.3.
Yes that number is not real. It would have smoked a grow in hours if it was.......

I am also considering adding some red wiggles worms for experimenting purposes. The composting bin I have is 20 gallons and I usually grow in 7gal pots one at a time. Was thinking about adding a handful of worms to the grow which I have done some research on.

Any suggestions on this?

JIMKSI64 · Jul 12, 2025

I never added worms to my food production areas as God tended to handle that part.
Lots of folks use it in living soil beds. Search Trainwreck and a couple of guys have tents with basically a raised bed perpetual system, rather perpetual ecosystem.

LoveGrowingIt · Jul 12, 2025

I've been reusing soil for several years. It has been an ongoing experiment. I encountered a few issues but believe I'm close to getting it right.

My most recent problem was acidification of the soil. Actively composting organic matter acidifies soil, but once organic matter is fully composted, it is neutral. Epsom salt (magnesium sulfate) also acidifies soil when the sulfur is released. Plenty of composting matter and regular use of Epsom salt caused my soil to gradually become too acidic. Adding between 1 or 2 tablespoons of dolomite lime per gallon of soil solved the problem.

Knowing how much nutrients to add when starting a new grow was another problem. When the pH is too low or too high, diagnosis of nutrient problems is difficult. When it's too low, micronutrient toxicity can occur due to excessive solubility. When it's too high, macronutrients precipitate out of solution and become unavailable. Thus, nutrient excess or deficiency can be caused by pH that is outside the range plants need. I just dealt with that because I overcorrected and had the pH a bit too high and the symptom was phosphorous deficiency. Correcting the pH corrected the apparent deficiency.

My first problem was deciding how much nutrients to add when starting a new grow. Excess nitrogen wasn't a problem. I reasoned that is because it's common to stop adding N during flowering, so most is consumed. Following the reasoning that nutrients needed would be those that were consumed during the previous use of the soil. Fortunately, organic growing methods are forgiving.

RGWD0202 said:
Double check me on this but I believe lime will lower your soil ph, but I don’t think you want to use dolomite. Could probably water in lower ph’d water maybe around 6 or so and see if that helps. Also add some gypsum to your soil if you haven’t yet.

Lime is calcium carbonate. Dolomite lime has both calcium carbonate and magnesium carbonate. Dolomite lime acts as a pH buffer and apparently raises the pH up to 7.0.

Gypsum is calcium sulfate, but I haven't yet confirmed that the sulfur from gypsum acidifies soil, even though my thinking is that it would do so just as magnesium sulfate does.

Oldchucky · Jul 12, 2025

Gypsum has no significant impact on the pH!

LoveGrowingIt · Jul 13, 2025

Oldchucky said:
Gypsum has no significant impact on the pH!

Thanks. Its impact is only slight in soil, so it generally isn't used to lower the pH of soil. Sulfates do tend to lower pH, though. I suppose it's arguable whether this or lime is the best amendment for increasing calcium. Calcium sulfate may not be the best choice if low pH is an issue. It's just something to keep in mind, I suppose. Progressively lowering of pH is one of the issues I've encountered in my reuse of soil. YMMV

Oldchucky · Jul 13, 2025

LoveGrowingIt said:
Thanks. Its impact is only slight in soil, so it generally isn't used to lower the pH of soil. Sulfates do tend to lower pH, though. I suppose it's arguable whether this or lime is the best amendment for increasing calcium. Calcium sulfate may not be the best choice if low pH is an issue. It's just something to keep in mind, I suppose. Progressively lowering of pH is one of the issues I've encountered in my reuse of soil. YMMV

According to my cheapo mail in soil report, my soil is always way out of whack! I just don’t tell the plants that or show them the report! And they do just fine! I’ve got low n and K. P, calcium, magnesium, sulfur, off the charts. A little low on the micros. But the pH is spot on at about 6.8! But I try and make my adjustments around the first of the year and let it compost! I don’t feed during the grow! It’s tough to keep 250 gallons of four year-old OF with amendments in balance! But I think the plants are smart enough to take what they want! and I don’t think they need nearly the fertilizer that everyone shoves down their throats! I think what is key to re-amending is getting it all done before you’re ready to use it!

Uncle_Strawberry · Jul 13, 2025

StalkerAF said:
I am also considering adding some red wiggles worms for experimenting purposes. The composting bin I have is 20 gallons and I usually grow in 7gal pots one at a time. Was thinking about adding a handful of worms to the grow which I have done some research on.

Any suggestions on this?

They are great for aeration of soil and the casings. But some worms also can destroy vital micronutrient. European is A positive but I used California night crawlers for my outdoor bed because of abundants

mancorn · Jul 13, 2025

Eledin said:
Wont all the nitrogen from the old roots be a problem?

Most growers remove the root ball, so nitrogen is the least likely nutrient to be in old soil. Sandy soils lose N through leaching, while clay soils lose N through denitrification. Nitrogen is also lost from volatilization (converted to ammonia gas) and with cannabis being such a hungry N user, the majority of N will be depleted from the soil. Most soil test (which aren’t cannabis specific) don’t even include nitrogen as part of a standard test - as there’s very little available at the end of the growing season for most crops.

mancorn · Jul 13, 2025

Oldchucky said:
I’ve got low n and K. P, calcium, magnesium, sulfur, off the charts.

Same here. N & K are the only nutrients I need and P is about 3x over optimum. Phosphorus really binds with other elements in soil, iron and aluminum at a lower pH, and calcium at higher pH. So real common to have an absolute shit ton of P and why it’s super important to make sure your pH is 6-7 to make sure the P remains accessible. But in soil it’s almost impossible to make a pH change with irrigation and why you need to adjust your soil pH in the off season.

Recycled amended soil high in ph/ppm

Recycled amended soil high in ph/ppm

StalkerAF

mancorn

Soil and Plant Nutrient Testing Laboratory : Soil and Plant Nutrient Testing Laboratory Services : Center for Agriculture, Food, and the Environment (CAFE) at UMass Amherst

JIMKSI64

Soil and Plant Nutrient Testing Laboratory : Soil and Plant Nutrient Testing Laboratory Services : Center for Agriculture, Food, and the Environment (CAFE) at UMass Amherst

Eledin

StalkerAF

Soil and Plant Nutrient Testing Laboratory : Soil and Plant Nutrient Testing Laboratory Services : Center for Agriculture, Food, and the Environment (CAFE) at UMass Amherst

JIMKSI64

RGWD0202

Eledin

StalkerAF

StalkerAF

StalkerAF

StalkerAF

JIMKSI64

LoveGrowingIt

Oldchucky

LoveGrowingIt

Oldchucky

Uncle_Strawberry

mancorn

mancorn

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