Blueberries...soil test results

riverman1June 28, 2012

Fellow Blueberry Growers,

I have about 20 blueberry plants in the ground. Because our native soils have a ph of about 7, for each plant, I dug a hole about 15 inches deep and 25 inches wide and filled it with a mixture of mostly fir bark and peat moss with a bit of native soil. Most of my plants have been in the ground two years, others just one year. They are growing well, lots of new growth, etc.

Like everyone else, I'm always concerned about the PH of the soil, particularly when I am applying at least two gallons of well water on each plant every other day during the summer months (June through mid October).

This spring I gave each of them a couple tablespoons of granulated sulfur. In 2011 I gave each of them three applications of granulated ammonium sulf, and this year thus far two applications of approximately 1.5 ounces of ammonium sulf sprinkled around the drip line.

Today I decided to have a soil test done. I have never had one done before and just wondered where the ph would be. An agronomist helped me do the collection, he used a soil probe to collect a sample from the around the base of several plants. The probe collects a sample in the first 12 inches of soil. We did a second soil collection on one of my plants that isn't doing quite as well as the others for comparison.

The ph of the random sample came back from the lab at 4.6. The plant not doing as well as the rest has a soil ph of 4.1.

The second part of the soil test will be ready in 5 days and will provide me with the bioavailibilty of 14 nutrients, nitrogen, phos, potassium, etc.

Anyway, I'm happy to report that despite using well water you can indeed control ph with nothing more than organic soils (peat and fir bark), a bit of sulfur, and ammonium sulfate. I have used very little sulfur on the plants and what I have used is only partially broken can still see most of it a few inches under the soil surface. I probably wont use sulfur at all next summer given these results.

Next summer I will repeat the test to get an idea of where I'm at with things. Given the current numbers, I don't think I will apply any more ammonium sulf this summer which will hopefully let the ph come up a bit.

For those curious, the soil test was $30 but I could have just had a ph test done for $10.


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Bradybb WA-Zone8

In one of your earlier posts,possibly from last year,I think there was mentioned about using an inexpensive pH meter that gets pushed into wet soil.I have a couple of those from Rapidtest.
If that is what yours was and if it's still available,is it possible to get a few readings and compare them with the soil test?I'd like to see how accurate these meters are compared to a known pH value. Thanks,Brady

    Bookmark   June 28, 2012 at 2:48AM
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Yes, you need to monitor the pH, but I would suggest getting a pen type pH meter for accuracy. Those cheap probes are wildly inaccurate.

Since your pH is a bit on the low side, I would continue watering with your water uncorrected and use urea instead of ammonium sulphate for fertilizer. But you do need to keep tabs on your pH, so get a decent pH meter. Mix soil samples with distilled water (or even rainwater will work) and let it sit for awhile. Then measure the pH of the water. The fact that you still have sulphur that hasn't broken down may mean your soil pH may actually drop a bit more as time goes by, so you need to keep an eye on it.

    Bookmark   June 28, 2012 at 9:10AM
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I too would be interested in seeing what one of the cheap ph meters show in your soil. I havent checked mine since last year but all my raised beds were in the low 4s and some in the 3s. The potted blues were alittle on the high side and I added some sulfer to those but havent checked them. Only if I notice some yellowing will I check the ph in the future. The fertilizer I use has 14% sulfer in it so hopefully 3 applications of this fert a year will be enough to keep the ph in range.

    Bookmark   June 28, 2012 at 12:40PM
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Take my advice or not, but I did comparisons between cheap probes and decent pen meters, including testing them in calibration solution. No comparison. They can be off by more then a full point in calibration solution, even more in soil as moisture level comes into play in readings. For neutral readings between 6 and 7 for vegetables in soil, they are not so bad, but when you get into blueberry range, they get much further out, and blueberries are much less forgiving of pH errors then tomatoes for example. A decent pen meter can be had for less then $100. Worth every penny.

    Bookmark   June 28, 2012 at 2:44PM
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I just did three tests with the Rapidtest around the base of one plant..........the one that the lab said had a ph of 4.1. I cleaned the probe between readings, the soil is very moist but not wet. The Rapidtest gave readings of 4.9, 5.1, and 5.3. So.......the Rapidtest is a full ph point off what is actually going on.

For $10 for a very accurate lab test I'm not sure it even makes sense to buy a meter. For what a good meter will cost me I can have a lab do the test for the next 10 years. For now I will just have mine checked every May or so and adjust from there.


    Bookmark   June 28, 2012 at 9:02PM
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gator_rider2(z8 Ga.)

Hanna has some good meters if say .1 accuracy that close as get I've had one many years 1988 its always right on money ever time.

    Bookmark   June 28, 2012 at 9:33PM
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What recommendations do folks have for a good Ph meter? The Hanna ones on Amazon look like they need multiple calibration solutions, storage solutions, etc. Any other options that are accurate. I'm up to 30+ blueberries in 3 different locations and would like an accurate one.

    Bookmark   June 29, 2012 at 11:40AM
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Bradybb WA-Zone8

Thanks,I'll check into getting a better meter or soil test done. Brady

    Bookmark   June 29, 2012 at 10:44PM
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The odd thing is I was out watering earlier and noticed that one of my plants has some leaves showing classic high ph problems, light colored leaves with dark colored veins. I tried the rapid test and it said 4.5 to 5.5 so not sure what's up with it. The plant is growing good right now.


    Bookmark   June 29, 2012 at 10:55PM
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gator_rider2(z8 Ga.)

Try some liquid feed grade iron teaspoon in gallon sprayer liquid iron should be in ever garden center in 8oz bottle once plants well establish iron normal there in soil so a recent soil test can show there plenty but show different in leaves. with iron spray change be fast couple days even. High ph does overcome iron uptake.

The plant is growing good right now.
Yes iron heavy and slow uptake.

Iron has tobe spray on ever leave iron interning one will not transfer to next leave.

    Bookmark   June 30, 2012 at 3:29AM
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alan haigh

Cornell sells pH kits here for around 15 dollars. They have one kit for readings between 5 and 7 and another for extremes at both ends. I don't know if extensions in other states have similar kits available or if you can purchase these from Cornell out of state.

While these kits aren't as accurate as lab tests, they are reliably accurate within an adequate range for home growers, IMO.

    Bookmark   June 30, 2012 at 5:59AM
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Got the full results back today for those that might be interested in seeing them. The agronomist felt that some of the problems the unhealthy plant may be experiencing are a result of potassium. As you can see the pH numbers came up just a bit which he says is typical after a soak.


    Bookmark   July 3, 2012 at 8:26PM
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I have an Oakton pH meter which works pretty good for me. Calibration is rarely off by more then .1. I keep it working well by storing the tip in storage solution, and using electrode cleaners a few times a year especially after doing soil tests which tend to dirty the probes. It's worth having accurate tests, especially for blueberries. Adding sulphur to the bed can change the pH pretty drastically over time. To me, sending out constant soil tests is pretty cumbersome.

    Bookmark   July 4, 2012 at 8:53AM
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I hear ya Copoman...nevertheless,

I don't see collecting a few tablespoons of soil in a paper bag and driving it a couple miles to the local conservation district once or twice a year anymore cumbersome than cleaning probes, calibrating, and storing the meter tip in a solution. One major advantage of the lab is I know the results are very accurate.

The advantage I see in having your own meter, assuming it's accurate, is that you can run tests whenever you want to. And, being the ADHD gardening spaz that I am, I would probably be running a test every other day! I may try one and just see how it goes.

If you don't mind me asking, what model by Oakton do you have?


    Bookmark   July 4, 2012 at 1:05PM
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I am using bromocresol green dye indicator to test soil pH in our blueberry beds. It works well, but the resolution is not so fine as can be obtained with a calibrated digital meter. The soil sample, about one tablespoon, is mixed with DI water to make a slurry, & this is filtered to get about 5ml of solution for testing. A drop or two of dye indicator is added. Yellow means pH = 3.8, blue means pH = 5.4, and green solution means the pH is around the mid-point, 4.6. This indicator is available mail order from HMS Beagle, but I'm sure there are other sources. A small bottle is two dollars.

    Bookmark   July 4, 2012 at 2:57PM
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gator_rider2(z8 Ga.)

Fe (iron real low get feed grade in 8 oz. bottle its in a lot garden centers).
use acid loving plant fertilizer this mainly for urea nitrogen so want change PH.

    Bookmark   July 4, 2012 at 10:09PM
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Bradybb WA-Zone8

Yeah riverman,now that I looked more closely at your chart,there are some things that are lower than optimal.Maybe check for an acid fertilizer with micronutrients.I have the Jack's Classic Acid Special that supplies those things. Brady

    Bookmark   July 4, 2012 at 10:40PM
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Not too much of a surprise that the micronutrients are lacking since I'm using primarily peat and bark. Wish I could buy some Jack's locally, hate having to order stuff like fertilizer. Thanks for the recommendations.


    Bookmark   July 5, 2012 at 12:27AM
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Riverman: I use an Oakton Ecotester pH2. I also have an Oakton ppm meter as well which is useful for testing fertilizer strength and water quality. I originally got these for hydroponic use, which I'm not doing anymore, but are quite useful in soil and container gardening as well.

    Bookmark   July 5, 2012 at 4:12PM
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Thank you..........

    Bookmark   July 6, 2012 at 12:36AM
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