Sounds like the products you mention are perfect to get the job done! Cottonseed meal may be a good fertilizer, as it is used for acid loving plants, but has no sulfur like say Holly-Tone which does. Dr Earth is another organic but I don't know exact ingredients. If you want a soluble Mir acid from miracle grow, non-organic. I use Holly-Tone and Micro-life right now. I'm always fighting to lower PH, so works for me.

Maybe show the soil test results to your local extension agency and they can help determine the right amounts to add. Brady

Sul-Po-Mag (potassium-magnesium sulfate) is neutral. It will not lower the pH. Iron sulfate, aluminum sulfate and elemental sulfur are acid-forming. Potassium and magnesium sulfates are the salts of strong bases and a strong acid, whereas iron and aluminum sulfates are the salts of weak bases and a strong acid. It is not the presence of sulfur that is responsible for acidity. It is the conversion of a sulfur form to sulfuric acid that lowers the pH, and this does not happen with neutral sulfates.

Note that epsom salt is magnesium sulfate, one of the two components of Sul-Po-Mag.

Espoma potash is potassium chloride, also a neutral salt. However, the sulfate ion is non-toxic to plants, whereas large amounts of chloride are toxic. Therefore, sul-po-mag is your best bet. The presence of excess sulfate in the soil is generally not an issue.

This post was edited by Slimy_Okra on Sun, Nov 30, 14 at 21:27

I would not mind looking into the reactions, to confirm, and I thought the Espoma product was potassium sulfate? Maybe not if they are calling it Potash.

This post was edited by Drew51 on Sun, Nov 30, 14 at 22:35

Espoma also carries potassium sulfate, but that is 0-0-50.

I don't understand how the sulfur in Sul-Po-Mag would not eventually turn to sulfuric acid by bacteria? Hard for me to understand how a sulfur product can be nuetral, ok, neutral until it is broken down. I guess though looking at the products it's going to be impossible to add anything without adding sulfur. Well the blueberries can take about 3.8 PH, but no lower. Maybe it would be better to use an organic source? Maybe use a non acid fertilizer like say Plant-Tone.
Nitrates are an issue, you need a nitrogen source low in nitrates.

Update:
I did look at some of the reactions and it seems it does not really acidfy soil. So Sul-Po-Mag might be the best product to use. Thanks Slimy_Okra, that is excellent info to know!

This post was edited by Drew51 on Sun, Nov 30, 14 at 22:59

It doesn't happen. Potassium sulfate and magnesium sulfate are salts of a strong acid (sulfuric acid) and strong bases (potassium hydroxide and magnesium hydroxide, respectively). When they dissolve, they ionize into potassium (or magnesium) and sulfate ions. All the sulfur in Sul-Po-Mag is in the form of these two sulfates (a needlessly complex name for a simple mixture of two salts, but that's another story!).

When something like iron sulfate dissolves in water, a small amount does not ionize, instead reverting to sulfuric acid and ferrous hydroxide. The hydroxide precipitates out, and the sulfuric acid reacts with native minerals. This forces more ferrous hydroxide and sulfuric acid to form until all the iron sulfate is used up.

It's not really intuitive knowledge - it's just because sodium, potassium, magnesium and calcium fall into the category of alkaline metals and their salts behave very differently from salts of heavy metals like iron, aluminum, manganese or other metals.

And then there's elemental sulfur, which bacteria react with oxygen and water to form sulfuric acid.

Edit: Glad to help! :)

This post was edited by Slimy_Okra on Sun, Nov 30, 14 at 23:01

Thanks for the chemisry lesson! I have a better understanding now, appreciate it! Your advice is very solid. I would follow it.

Is the sulfate ion stable? What happens to it?
Sulfur alone will change to sulfuric acid in 6 months to a year, so is of concern. Again why I was concerned about the sulfur content, OK, so it doesn't form sulfic acid quickly, if sulfur breaks away from the oxygen, it will be metabolized by bacteria. and possible even the sulfate will be used by bacteria. I use sulfur to acidify my soil long term.

The sulfate ion is stable, yes, if bound to magnesium, potassium sodium or calcium. So there is no risk of it being used by bacteria. It is already in the oxidized state and has already been "used up". All the sulfur in Sul-Po-Mag is in the sulfate state; none of it is present as elemental sulfur. IF you want to lower the soil pH, you'll have to get elemental sulfur or one of the acidic sulfates like iron sulfate.

OK, thanks very much for the info! Sorry it's been a long time since chemistry 101.

You don't need much chemistry if you mulch them with wood chips- preferably from the arborists hopper. I know it will straighten up any K deficiency (it is extremely mobile) and you can make a quick search about the mag issue- I expect it will clear that up as well. Potassium also leaches out of leaves even while they are still on the tree as I recall. Fallen leaves release plenty of it. Mulch also increases the ability of plants to take K up.

Blueberries thrive up into the mid 5's so you don't have to worry much about any mulch bringing up the pH.

It's a good idea to mulch, and I would use Sul-Po-Mag and also mulch. As this is really a long term problem. But you can solve it by regular feedings. Blueberries love to be fed, so if you use a good organic about twice a year all should be fine. Also you might want to water with tap water to raise the PH. Most tap water is basic, acid eats pipes and most cities keep the tap water basic. If you can raise the PH a little you can use say Holly-Tone. I like that product, but many good ones are out there. Holly-Tone is very balanced as you asked. So is Dr Earth fertilizer for acid plants. Another interesting fertilzer, non orgaic is Gertens 3 lbs Acid Loving Controlled Release Plant Fertilizer 24-5-10 .
It also is a complete fertilzer. This would be a great product for blueberries in pots!
All of these can be looked at on amazon.

If the soil test was done by your local extension agency, it will tell you what to add and how much.

Drew, how do you know this is a long term problem not resolvable with mulch alone? Wood chips usually contain ample magnesium- I just double checked my hunch with a search on the subject. I am certain they will supply adequate K from day one because it is so mobile.

I've never added anything to my blueberries besides mulch and a dose of my own urine in early spring and they've rewarded me with 25 years of vigorous growth and production.

I'm not saying beginning with amendments suggested by a soil test is not the wise thing, only that needs will almost certainly be drastically altered by the use of an organic mulch. I seriously doubt either nutrient will need to be regularly added in the future if the plants are mulched.

Drew, how do you know this is a long term problem not resolvable with mulch alone?

Well most do not urinate on their plants, and need some way to be fed. It wasn't worded very well. Guilty as charged.
I'm also concerned about micro-nutrients, as in my area we are low in manganese. Any wood from the area will be too. I have no way of knowing if the wood suffers from any deficits. I know Holly-Tone is a complete source of nutrition and it would ease my mind. You offered no source of nitrogen in you first post, urinating on my plants would result in my arrest in my neighborhood.
I myself do not use woodchips. I have to pay for them. And for me I fight to keep the ph low. I would not use them for that reason. Not that chips are basic, it's just not acidic. I would rather pay for a more quantified fertilizer, blame it on the lab rat in me.
Using wood chips though is a good idea in this situation, oh wait I already said that.

I must admit I find your solution rather unique and quite humorous too. I usually try to avoid breaking the law when feeding my plants. I realize laws vary, here it is illegal. My bad for assuming it was in this situation, I guess I should have asked. I myself would avoid it even if legal. I'm on a couple of medications, and would be concerned about the quality of the urine. I would avoid if you're on any antibiotics at the time too. most are broken down but a few do leave the body intact. Especially say if you have a bladder infection, that antibiotic is meant to enter the bladder intact. I forget which one it is? It still may be fine, I really do not know? I try to avoid unknown situations.
Also an unknown is the amount of nitrogen I'm adding. It would be trial and error, like would you suggest 2 minutes of fertilizer? I guess that would depend on the flow rate of your stream. When I was younger one minute would probably suffice. I could take a measuring cup with me. Let us know the rate per plant. I would not want to go willie-nilly on my plants.

I also found the chemistry useful as I avoided using sulfates on my basic loving plants. Now I know I can use some. I also like to know what I'm adding does, and so as general info is very useful.

This post was edited by Drew51 on Tue, Dec 2, 14 at 8:17

Just because the soil is deficient is no sign at all the wood of trees growing in it is. Trees have massive root systems enhanced by mychorizal relationships and tend to find what they need or show symptoms.

My approach is to amend as needed only. Others go by other methods. I strongly doubt a mulched plant will have deficiencies in minerals always found to some degree in wood unless it is a matter of balance. But I don't have experience in soils beyond the northeast and far west, although I've put my hands in a wide range in those regions. In all my years I've never had visible nutrient deficiencies with any plants I manage besides N.

Urine as fertilizer is an immensely amusing subject, but it is just as potent as a fertilizer. We excreet the majority of shuttled K, P and N via this route. I don't expect trace amounts of your drugs would last in the soil long and it is highly unlikely they would have any affect on plants.

I doubt urine is illegal to use as fertilizer. It is almost sterile and non-toxic. It is an agricultural comodity in China commonly used even for food crops.

I haven't used night soil since the '60's when I just didn't know any better. Pooped in a bucket, made a slurry and fed it to pot plants. Much as I loved the plants it was something I only tried once.

If you are sure the pH is too low, why not add Ag lime to raise the pH. Use Ag lime, not Hydrated Lime. Hydrated lime is used in construction and is caustic. Hydrated lime changes pH suddenly and can burn leaves and roots.

As you raise the pH, mg and potash will both become more available to the plant. This might fix the mg deficient problem without having to add mg. Adding 1/2 pound of lime to 100 sq feet of sandy soil should raise the pH 0.5. It takes 3 lbs per 100 sq feet to raise the pH 0.5 in loamy soils.

Normally you would never add lime to Blueberries. The lime in tap water in limestone area (western US and Florida) is the reason it raises the pH to excessive levels.

You might also take a soil sample at the 6" to 12" level. This layer might have a higher pH and give the blueberries the mg and potash that they need. Levels of pH also changes throughout the year. The extension service suggest taking the soil sample at the same time each year. The moisture content at the time of taking the soil sample also affects pH.