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off season soil acidification for blueberries?

Posted by oldryder (4), MN (My Page) on
Wed, Dec 26, 12 at 19:39

just wondering if there is any value to adding soil acidifier now (winter here in MN) it would be dispersed into the soil very slowly with each partial melt until the full spring thaw.

I have blueberries in soil amended with 50% peat two years ago and treated with sulfate. some plants have done OK, some others still appear to need more acid soil. lowest Ph I got was 6.0

I have aluminium sulfate or ammonium sulfate for treatment, no sulfer although I'm wondering if I should buy some.

suggestions or advice welcome.

Follow-Up Postings:

RE: off season soil acidification for blueberries?

Some Sulfur could be sprinkled around and worked into the soil a few inches to get a head start for next year.
I'd use Ammonium Sulfate in the Spring and early Summer.
What's your irrigation water's pH? Brady

RE: off season soil acidification for blueberries?

Aluminum sulfate is supposedly lower the soil PH but it takes long time to make any noticeable change don't expect that using these material will change the soil PH overnight. I think it takes time also the water is very important some people think adding a spoon of vinegar to the water will help. I tried everything and feel that nothing got changed.

RE: off season soil acidification for blueberries?

I'd read this past year of people liquifying AlSu and pour the mixture around the base of the plants, for a quicker response in the soil's pH.
I've done it now, but I can't say if it works or not. :)

RE: off season soil acidification for blueberries?

hey z8 brady ...

you crack me up.. working the soil in z4 MN ...

ITS FROZEN SOLID ... lol .. and will be thru at least late march ....

so he is wondering if spreading it on frozen soil.. with the intermittent thaws.. might do something ...

my first thought.. is.. if it wont all wash away .. by the time the ground thaws to depth ...

sounds like time to mark off a portion.. and experiment ... if you dont get an answer ...


RE: off season soil acidification for blueberries?

  • Posted by ericwi Dane County WI (My Page) on
    Thu, Dec 27, 12 at 10:42

It is easy enough to acidify the soil around blueberry shrubs with agricultural sulfur, the bacteria do the work, but they need warmth and moisture to complete the process, so nothing will happen until the weather warms up. What is not so easy is getting an accurate pH reading-I am using bromocresol green solution, which indicates blue at pH of 5.4, yellow at pH of 3.8, and green when the pH is around 4.6. A tablespoon of dirt is mixed with enough pure water to make a slurry, and the mixture is filtered with a coffee filter to get a small sample. That is what you test, with a drop or two of bromocresol green. Here in Madison, it might take about 1/2 cup of agricultural sulfur to lower soil pH over a two year period, per shrub.

RE: off season soil acidification for blueberries?

No harm in it except you may lose track if some washes away. You don't actually have to demonstrably alter soil pH to allow plants access to iron. Even broadcasting pelletized sulfur on the surface has been shown quite affective at eliminating iron deficiency related chlorosis well before a change in soil pH is detected. The iron becomes available near the surface and is absorbed by roots there.

Carl Whitcomb found clear evidence of this in experiments of treating chlorosis on pin oaks with surface applications of sulfur and the condition was alleviated within a couple of months although it was impossible to detect a change in pH. You could probably find information about this on the internet and it is in his book "The Establishment and Maintenance of Landscape Plants".

I have some anecdotal experience of this also working for blueberries which would seem logical anyway.

RE: off season soil acidification for blueberries?

We are in Wisconsin, and I don't think it's worth doing now. I would wait until spring and the frost is out of the soil. I would add sulphur but not at a higher rate than 400#/acre a year. But sulfur will not start working until the soil warms up. If the condition is bad, I would use iron sulfate at about four times the rate for sulphur if your planting is small. You can use ammonium sulphate to fertilize, but avoid the aluminum sulphate. I would advise foliar feeding of a chelated iron, annual soil and foliar analysis until the soil improves.

RE: off season soil acidification for blueberries?

everyone thx for advice. Obviously I know it's winter here but I miss doing things with my plants. I'll go with sulfer as soon as things thaw ... in about 3 months.

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