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Test ph at home

December 6, 2018

Are there *reliable* ways to test soil pH at home? I’ve tried strips and solutions, but the soil itself discolors the water to a point where it has been difficult to get a reading.

I paid for a commercial soil test in Fall, 2016 and got results in the 4.8 – 5.2 range. After liming and using the vegetable garden for a season, I tested again that fall and got 6.3. Which is good.

The issue is that I don’t know how long it will last, or when I will need to add lime again. We had a very rainy year (60” compared to the normal of about 40) so I’m concerned that the soil leached a lot, and became pretty acidic again. My soil is a well drained loam with a fairly low CEC of 15. It costs more to keep doing soil tests than it does for the amount of lime I would need!

Any ideas? Or – any guesses how often I will need to lime? I last limed in Spring 2017.

This is for my vegetable plot.

Comments (15)

  • gardengal48 (PNW Z8/9)

    I have found the home test kits (the little vials, like this Rapi-test kit) are remarkably accurate for their cost, provided you use distilled water. Regular tap water may artificially influence the test.

    Follow the instructions fully and do not use too much soil in your test samples.

  • daninthedirt (USDA 8a, HZ10, Cent TX, Sunset z30)

    I haven't had trouble with strips. But you have to do it right. Mix soil and water to level of soil, swirl around. Let it settle for half an hour. Decant, or better yet, filter some of the liquid with a coffee filter. The result should be a pretty clear liquid that won't visibly foul the test strip. By all means use distilled water. Strips are very economical and accurate enough.

  • kokopellifivea

    I haven’t tried the strips yet. The cheap test meters aren’t much. I had the test tube with distilled water, but that consistently overstated ph.

    If it’s “mission critical“ pay for a proper soil test.

  • toxcrusadr

    I've always been an advocate of inexpensive pH buffers that can be made from common ingredients to calibrate your meter. But reading the above posts really makes me think that if you haven't already bought a meter, or if it just sucks, it's better to use the strips and filter your water sample first if need be. Just be sure to get appropriate strips - a fairly narrow range where your pH falls, not the 0-14 strips you used in junior high chemistry experiments.

  • daninthedirt (USDA 8a, HZ10, Cent TX, Sunset z30)

    That's an important point about getting limited-range pH strips. I've used medical pH strips that are intended for testing urine or saliva. These work in the range 4-9, which should cover just about any kind of soil. You can get these reasonably inexpensively in a drug store. They're supposed to be accurate to about a quarter of a pH unit.

  • wayne_5 zone 6a Central Indiana

    I have a Rapid Test probe. I think it works pretty well in the range below ph 7.3

  • daninthedirt (USDA 8a, HZ10, Cent TX, Sunset z30)

    I think Rapid Test is for test strips. You mean RapidTest (no space), in case people want to look it up.

  • perennialfan275

    Many colleges and universities will do a soil test for free or very cheaply. If I were you I'd forget about the pH strips and just contact someone at your nearest college/university. They will probably be able to give you the most accurate information.

  • Tim C (Z8b, So Cal)

    a question on Ph test meter you can buy online. Are they accurate enough?

  • gardengal48 (PNW Z8/9)

    "Are they accurate enough?" Only if you are prepared to shell out some bucks. The cheap ones are pretty much worthless.

  • toxcrusadr

    Any pH meter should be calibrated or, if it isn't calabrate-able, at least have its calibration checked. That involves pH buffer solutions which have to be bought (although there are some DIY options), and they have to be fresh as they don't last forever on the shelf.

    So, the cost and hassle may be more than it appears to be.

  • daninthedirt (USDA 8a, HZ10, Cent TX, Sunset z30)

    Use strips. They're cheap, reliable, and always right, and they are plenty accurate enough.

  • kokopellifivea

    This was my experience after my ph strips arrived. They correlated very closely with known values obtained from university tests.

    I used narrow band strips, Ph 4-7. I was careful to use distilled water to make a slurry of my soil sample. I also allowed about 20 minutes for the chemistry to settle down before testing. I’m not sure if that was enough time or more than I needed.

    Got mine off eBay for like $6.

  • toxcrusadr

    The chemistry shouldn't need more than a few seconds, it's the fine suspended sediment that has to settle so you can see the strip color.

  • daninthedirt (USDA 8a, HZ10, Cent TX, Sunset z30)

    You need to decide what you really want. If you want 0.1 pH accuracy, then get a good meter and calibrate up the kazoo. If you want a quarter pH accuracy, then strips are called for. I guess if you want to track pH accurately as you add amendments, the former might be helpful. If you just want to tell the difference between 5 and 6, a meter is a waste of money.

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