# Interpretation of Soil Test Results



## bbroderi (Jun 9, 2021)

Hi all,

I had a soil test (mysoiltesting) on 3/31 which showed a nitrogen level of 4.8 ppm, and listed optimal as 7.0-18.0, and a potassium level of 21.77 ppm with optimal as 38.0-72.0. What are these "optimal" ranges based on? pH was 5.6 (listed as low), which should be optimal for centipede, and the micro's were all low too. I realize the test is generic, but I can't really find any turf specific nutrient level. I did apply 1/2 lb of 15-0-15 in early April, but I haven't done another test since. I'm new to testing, and this site was recommended, but need a little guidance.


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## Austinite (Oct 4, 2018)

The ranges are supplied when you register the kit and select the sample type such as Turf & Lawn, Vegetables, etc...

In the case of Turf & Lawn, the range is based on a wide variety of grasses. So while one grass may be optimal outside of listed ranges, others will be in range. Most grasses are studied very well and info should be out there. Not too familiar with Centipede, but in my case, I can find ideal levels for just about any Bermuda Variety.


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## Mightyquinn (Jan 31, 2017)

@bbroderi I moved this to the soil forum to get more visibility.


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## Virginiagal (Apr 24, 2017)

I doubt anyone is going to be able to help. Read this:
https://thelawnforum.com/viewtopic.php?t=16135


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## hawkman248 (6 mo ago)

I don't believe there is an accurate test for soil nitrogen that works well in the southeast. There was such a test (Illinois Soil Nitrogen Test, ISNT) but we found at NC State University that it wasn't dependable here - I think based on higher rainfall and temperatures.

There is a lot information on NCSU's extension pages (NCSU's Turffiles site being one of them - they have quite a turf program). Also, I'm not sure where you got your soil test but NC's Department of Ag & Consumer Services (NCDA or NCDA&CS) also has a lot of info. The NCDA* also* uses a Mehlich-III extraction which produces a result in ppm (parts per million). Other states and private labs use a Mehlich-I extraction and report results in lb/acre. Waypoint uses Mehlich-III. Waters uses Mehlich-I. My point is that your results are in the same units as that of NC and you'll be able to compare easier.

For nitrogen, I'd consider going with a general recommendation from your local extension or land-grant university. No need to have a precise amount imho - heck, I doubt the measurement is precise anyway!

Here is a link to NCSU's centipede lawn maintenance calendar. The author is a standup, reliable, successful turf specialist. He also taught me a statistics class. 

https://content.ces.ncsu.edu/centipedegrass-lawn-maintenance-calendar


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