# PH Meter vs Soil Test



## Alex1389 (May 23, 2018)

Can anyone comment on the accuracy of soil PH meters that you can buy off Amazon or at big box stores like the one pictured below?

My PH meter seems to line up with the Logan Labs soil test PH reading for my back and side yards, but the front yard is a different story.

PH on the probe was about 5.5 and Logan Labs came back at 6.6.

We've received a ton of rain this August and my lawn has taken on a lime green color in several areas in the front, while the back and sides remain pretty OK. Front lawn has a pretty good slope towards the road.


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## jessehurlburt (Oct 18, 2017)

Soil tests from my local university are $12. For that I get my macros, micros and Ph along with specific recommendations. Seems like a bargain so I never looked into those meters.


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## Delmarva Keith (May 12, 2018)

I'd look at it like this: how much labor and materials does it cost to adjust ph or how much wasted money and effort chasing issues if the ph is not in the optimal range but you don't know that. If the little ph meter is off, it will end up costing a lot more than an accurate lab soil test.

For the lime green color, that's usually either nitrogen or iron deficiency (or both). You can make two small test plots on the front lawn, apply N to one and iron with a little bit, 2 oz per 1,000, of ammonium sulfate (enhances iron uptake) to the other. One or the other or both will likely green up very noticably. My guess is it needs N and is behaving differently from the back and side yards due to a difference in CEC of the soils, or differing N use from different growing conditions (amount of sun, water, etc.).

If neither test plot greens up, post your soil test. It needs something.


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## Alex1389 (May 23, 2018)

Delmarva Keith said:


> I'd look at it like this: how much labor and materials does it cost to adjust ph or how much wasted money and effort chasing issues if the ph is not in the optimal range but you don't know that. If the little ph meter is off, it will end up costing a lot more than an accurate lab soil test.
> 
> For the lime green color, that's usually either nitrogen or iron deficiency (or both). You can make two small test plots on the front lawn, apply N to one and iron with a little bit, 2 oz per 1,000, of ammonium sulfate (enhances iron uptake) to the other. One or the other or both will likely green up very noticably. My guess is it needs N and is behaving differently from the back and side yards due to a difference in CEC of the soils, or differing N use from different growing conditions (amount of sun, water, etc.).
> 
> If neither test plot greens up, post your soil test. It needs something.


Thanks for the info, @Delmarva Keith. I'm assuming that we cannot 100% rely on these soil meters based on what you've written. Given my sandy loam and low soil CEC, I'm starting to wonder if I'm better off conducting a soil test early in the spring prior to applying any products and again in August when my inputs are low due to the summer heat.

As for my current situation, yeah I'm definitely not applying any more lime. The Logan Labs results have made me super cautious about applying any more lime this year, and I'll take a look again next spring when I have another soil test done through Logan. Starting the fall blitz here this week, so I'm hoping the color improves quickly. Soil CEC is 6.21 in the front, so I'm thinking all of this rain did a number on whatever N was left in the soil.


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## BenC (Mar 27, 2018)

I have a couple field pH meters, mine are a couple hundred bucks apiece and are pretty accurate. I calibrate them frequently. I always tell folks that they shouldn't count on the field meters (no matter the cost) for accuracy but rather to track relative changes in soil pH over time if they are inclined to using one and will keep track of results. Lab results will almost always be more accurate, but even labs screw up once in awhile. Any lab I've toured has had low skilled, seasonal workers processing samples.


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