# Calcium & Magnesium Test Strip Experiment



## Grizzly Adam (May 5, 2017)

Today I spent a little time in my workshop lab to work on an idea I had. I combined one part prepared soil (from my big test soil bin) and one part distilled water and set it to stir for 5 minutes on the stir plate. I then let it sit to settle, poured the top portion into a test tube and allowed it to settle one more time until nearly clear. After about 10 minutes, I dipped a calcium test strip and a total water hardness (calcium plus magnesium) strip and recorded the results. I then verified the results with additional strips. I did the same with the distilled water and verified that it had no calcium or magnesium.

I came out with 120 ppm calcium and 150 ppm total hardness, which would mean that there is 30 ppm magnesium (according to the test). However, I am not sure that I have the test properly calibrated-- I could need more or less of the distilled water to get an accurate result.

So now I need to come up with a way to calibrate the test. I think the next step will be to order in CaCO3 to spike the distilled water to a known amount and adjust the strength of the solution until the test strips correspond with the known quantity within the water.

Has anyone else tried similar tests?


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## bernstem (Jan 16, 2018)

What are you trying to determine?


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## Grizzly Adam (May 5, 2017)

bernstem said:


> What are you trying to determine?


I just enjoy science in general and am trying to find an easy home calcium test.


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## bernstem (Jan 16, 2018)

You may find a test for soluble N/P/K to be more useful than Ca or Mg. @Ridgerunner has a lot of knowlege on soil testing and the laboratory procedures used. I pinged them to this thread as they may have some resources for you to read up on soil testing methods.


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## Grizzly Adam (May 5, 2017)

I have already been doing NPK and PH testing for a number of years. I am working on adding new tools to the toolbox.


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## Ridgerunner (May 16, 2017)

Google Search texts by R. N. Carrow for titles on topics that you are interested in exploring.

Best Management Practices for Saline and Sodic Turfgrass Soils: Assessment and Reclamation
by
Robert N. Carrow, Ronny R. Duncan

Don't let the title (Saline and Sodic) throw you, it contains excellent explanations of test methods and a great gateway to other resources/research/studies through the bibliography and footnotes.


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## Ridgerunner (May 16, 2017)

Remember , test results are useless if they haven't been proved to be both correlated and calibrated.
Makes little sense to me to re-invent the wheel. Use one of the established test methods that have already been correlated and calibrated.In this case, research "Saturated Paste Test."


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## g-man (Jun 15, 2017)

^+100 Reproducibility and Repeatability

A commercial lab will test your soil for $15-30 and give you a lot more information.


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## Lawn Whisperer (Feb 15, 2021)

Grizzly Adam said:


> I have already been doing NPK and PH testing for a number of years. I am working on adding new tools to the toolbox.


Look into Soil Infiltration Test, Bulk Density Test, and Electrical Conductivity(EC) Test.


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## Grizzly Adam (May 5, 2017)

Lawn Whisperer said:


> Grizzly Adam said:
> 
> 
> > I have already been doing NPK and PH testing for a number of years. I am working on adding new tools to the toolbox.
> ...


Thanks, I was unfamiliar with the Bulk Density Test.


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