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DIY ph testing....is it worth it ??

Posted by texasjack Houston Tx (My Page) on
Mon, Jun 25, 12 at 14:37

I'm a container tomato hobbyist and retired Mechanical Engineer. I'm fascinated by the extensive highly technical discussions on plant biology, chemistry, soil mechanics, etc. I find it amazing that anyone can ever grow a successful plant given every thing that can go wrong.How did the Mesoamericans do it without the benefit of Forums, Al, Dave, et. al.( Bless them)?

Is it worth the effort for a hobbyist who doesn't want to invest in lab quality equipment to even bother with the DIY single test kits or low end (cheap)meters? Given the dynamic nature of soil ph, macro and micro nutrient levels, etc. sending a sample out to A&M seems futile.

Any thoughts would be welcome.

Texas Jack


Follow-Up Postings:

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RE: DIY ph testing....is it worth it ??

Best is a midrange level equipment that may not be lab spec, but can give you pH readings within .1 or .2 of accuracy. Even strips can do this, and yes it's worth doing. TDS meters are also just as important for testing water hardness, and fertiizer levels.

What a person doesn't want is one of those cheap stick in the ground probe pH meters. They can be totally unreliable and worthless. Runoff water is not a good test either. Best to soak a soil sample in distilled or even rainwater for a reasonably accurate reading. Getting within .2 pH is close enough.


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RE: DIY ph testing....is it worth it ??

Agreed, the stick meters you buy at the big box stores are terrible. pH strips work well, and the indicator drops sold for hydroponics are versatile and useful as well. Either of those options is relatively inexpensive and more than accurate enough for a hobbyist.

Neither of these things is *required* if you're not seeing obvious nutrient deficiencies. If growing in the ground, soil surveys available online can give you useful measurements. Your water provider can give you the important information on TDS, pH, hardness, etc. The biggest problem for us in Houston is the bicarbonate alkalinity of our water and somewhat high sodium. We usually get enough rain to flush out containers regularly, so it's not as bad as it seems. Slightly sensitive plants like Ixora, Gardenias, many orchids, Citrus, some Roses, the popular landscape azaleas, benefit from acidification of water or the use of rainwater, or at least require occasional chelated micronutrients (mainly iron). Very sensitive plants like blueberries, the unimproved azaleas and rhododendrons, vanda orchids, camellias, require acidification or rainwater.

In containers, you can get a working estimate of the pH of your media just by knowing whats going into it. Following Al's 5:1:1 recipe, with the recommended amount of dolomite, works well. Just be cognizant of what your source of bark fines is, and whether or not it comes pre-amended for pH. For example, I use the an "organic compost" sold at Lowe's for my pine bark... but the ingredients listed on the back make clear that its been premixed with fly ash to bring up the pH - so I don't add any additional dolomite, and use calcium sulfate (gypsum) and occasional magnesium sulfate (epsom salts) instead.

Once you learn the particulars of your environment and conditions, things become much less complicated.


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RE: DIY ph testing....is it worth it ??

I have a degree in chemistry, and I have never tested the pH of my soils in my life.

That might seem kind of odd, but I think with good soils and applications of good compost, it's not such a big deal.

I suppose I might do it in the future, if I knew I was starting from extreme conditions, but I haven't met them so far.


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RE: DIY ph testing....is it worth it ??

Is the ph tester sold by lee valley tools no good, cheap, unreliable?


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RE: DIY ph testing....is it worth it ??

Jack, in my experience, it is well worth it to check your soil pH. I grow a lot of pawpaws, starting them in containers. One of my mix recipes included sand (I don't use this anymore). I noticed the trees in this mix were doing poorly. Pawpaws are like blueberries--they thrive in low pH. My water is very alkaline, so I add acid to my water. Someone at a very prestigious university told me the problem couldn't be the sand: "sand is neutral pH." I finally decided to check all my mixes with the pour through method and pH strips. It was amazing! Every mix with high pH, including the sand mix--was hurting my trees. The sand was a limestone material. Low pH mixes, including 5-1-1, were good.

So yes, distilled water and strips are cheap, and the test is accurate and very educational! Go for it.

Marc


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RE: DIY ph testing....is it worth it ??

Try the digital ph meter sold at Starkbros website. I had tried a few others and was disappointed, but that one really works. i.e. tested my soil at 7 but when put in newly purchased blueberry plant read 4.8. Also, when stuck in tap water reads 7, however when 4 tbsp vinegar is added to 2 ga. water reads 5.2


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