Selecting a Soil Test Laboratory

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Selecting a Soil Test Laboratory

Post by Ridgerunner »

Some things to keep in mind when selecting a Soil Test Lab:

1. If you aren't willing to put the effort into proper sampling, it doesn't mater what lab you use. You might as well use one of the home tests sold at Lowes, because sh@t in = sh@t out no matter how good the lab. Studies (my interpretation) have shown that 8 samples from each 3000-3500 square feet section of soil will result in a final sample that has a probability of being representative of the entire 3000 sq. ft. area 90% of the time. Each additional sample above 8, will only improve the probability by 1-2% with diminishing improvement with each additional sample. However, each fewer sample will dramatically reduce the probability that the final mix of samples will be reflective of the whole 3000 sq. ft. plot tested with 4 or fewer total samples having about a 50% or less chance of accurately reflecting the 3000 sq ft area. So if you aren't willing to put the effort in to sample correctly, it doesn't matter which lab you select. Just use a Lowes home test.

2. Most labs will do a decent job of testing and provide useful results. So, 9 out of 10 times whatever lab you chose will suffice. Soil Savvy or MySoil are not ones I would use. If you want some assurance that a lab has at least met some verifiable standards of accuracy, reliability and repeatability, select one of the labs that participate in and are NAPT/PAP certified: https://www.naptprogram.org/pap.

3. Identify which testing method you want to use. There are a number of nutrient extraction methods. This is dependent on the pH of the soil or, in some cases, an item of personal preference. I happen to be old school and prefer: ammonium acetate for the Base Cations: K, Ca, Mg (gives accurate results no mater the soil pH), Bray/Olsen/Mehlich for P (phosphorous-choice of method is very dependent on the pH of soil - use Mehlich or Bray if pH is below 7.2 and use Olsen if pH is above 7.2), and DTPA for micro-nutrients. However for most turf enthusiasts, I would recommend Mehlich3 if soil pH is below 7.2 (in higher pH soils Mehlich 3 can result in drastically inaccurate Ca and sometimes Mg levels. In higher pH soils, pH >7.2, use ammonium acetate).
Mehlich 3 is the method preferred and employed by the vast majority of turf research (university and PACE) and it will aid in simplifying comparisons and drawing conclusion between the current research and your soil results. If you wish to employ the MLSN/build/maintenance program I describe as the "Somewhat EASY, SIMPLE METHOD for Determining Fertilizer Rates and Nutrient Levels to Achieve Optimal Nutrient Levels" in my soil test thread then it isn't really critical which measuring stick/test you use as long as it's appropriate (for the pH) for your soil.

4. Look for a lab that offers a comprehensive battery of tests. Individual tests that they provide for testing for things like EC (electric conductivity-measurement of soil salinity), Buffer pH (BpH-to determine the amount of lime needed to raise pH), soil microbial health (Solvita), tissue testing or soil carbonate content testing (to determine the amount of Sulfur that would be needed to lower pH). Items that you may have a need to test for in the future.

5. Look for a lab that offers a variety test suites. Do they offer suites that including "comprehensive" testing for the Primary, secondary, and trace nutrients? Do the have a suite that includes Buffer pH? Soil Salinity? Do they offer pared down suites that only test for the primary nutrients at a reduced cost? (Although I would recommend a very comprehensive testing suite for the first test done (test primaries, secondaries, trace/micros, salinity and BpH etc. to see where your soil is at/more information makes for better decisions), after which, if your micros and secondary nutrients are within range, you don't need to test them yearly. Run that test every other or third year. Save money and only test the Primary nutrients in the intermediate years.

6. Look at the amenities the lab provides. How easy is it to access, understand and use the portal/site and forms. In addition, some labs will store your yearly results and allow you to run comparisons of individual nutrient changes from one year to the next.

7. Compare fees between labs. (cheapest isn't always best, although don't get fleeced either)

8. Once selected, use the same lab for each subsequent test. It will help reduce variability in results when you make comparisons from year to year.

Quick Summary:
1. Pick an NAPT/PAP lab.
2. Sample correctly.
3. If soil pH is below 7.2, use the Mehlich 3 method.
4. If soil pH is above 7, use the Ammonium Acetate and Olsen methods.
Last edited by Ridgerunner on Fri Dec 18, 2020 9:06 pm, edited 11 times in total.

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Re: Selecting a Soil Test Laboratory

Post by osuturfman »

Top notch!

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Re: Selecting a Soil Test Laboratory

Post by g-man »

Great write up. I linked it to the top folder thread for future reference.

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Re: Selecting a Soil Test Laboratory

Post by bushwacked »

Ridgerunner wrote:
Wed Jan 02, 2019 4:29 pm
Some things to keep in mind when selecting a Soil Test Lab:

1. If you aren't willing to put the effort into proper sampling, it doesn't mater what lab you use. You might as well use one of the home tests sold at Lowes, because sh@t in = sh@t out no matter how good the lab. Studies (my interpretation) have shown that 8 samples from each 3000-3500 square feet section of soil will result in a final sample that has a probability of being representative of the entire 3000 sq. ft. area 90% of the time. Each additional sample above 8, will only improve the probability by 1-2% with diminishing improvement with each additional sample. However, each fewer sample will dramatically reduce the probability that the final mix of samples will be reflective of the whole 3000 sq. ft. plot tested with 4 or fewer total samples having about a 50% or less chance of accurately reflecting the 3000 sq ft area. So if you aren't willing to put the effort in to sample correctly, it doesn't matter which lab you select. Just use a Lowes home test.

2. Most labs will do a decent job of testing and provide useful results. So, 9 out of 10 times whatever lab you chose will suffice. Soil Savvy or MySoil are not ones I would use. If you want some assurance that a lab has at least met some verifiable standards of accuracy, reliability and repeatability, select one of the labs that participate in and are NAPT/PAP certified: https://www.naptprogram.org/pap.

3. Identify which testing method you want to use. There are a number of nutrient extraction methods. This is dependent on the pH of the soil or, in some cases, an item of personal preference. I happen to be old school and prefer: ammonium acetate for the Base Cations: K, Ca, Mg (gives accurate results no mater the soil pH), Bray/Olsen/Mehlich for P (phosphorous-choice of method is dependent on pH of soil), and DTPA for micronutrients. However for most turf enthusiasts, I would recommend Mehlich3 if soil pH is below 7.2 (in higher pH soils Mehlich 3 can result in drastically inaccurate Ca and sometimes Mg levels. In higher pH soils, pH >7.3, use ammonium acetate.). Mehlich 3 is the method preferred and employed by the vast majority of turf research (university and PACE) and it will aid in simplifying comparisons and drawing conclusion between the current research and your soil results. If you wish to employ the MLSN/build/maintenance program I describe as the "Somewhat EASY, SIMPLE METHOD for Determining Fertilizer Rates and Nutrient Levels to Achieve Optimal Nutrient Levels" in my soil test thread then it isn't really critical which measuring stick/test you use as long as it's appropriate for your soil.

4. Look for a lab that offers a comprehensive battery of tests. Individual tests that they provide for testing for things like soil salinity (EC), Buffer pH (BpH-to determine the amount of lime needed to raise pH), soil microbial health (Solvita), tissue testing or soil carbonate content testing (to determine the amount of Sulfur that would be needed to lower pH). Items that you may have a need to test for in the future.

5. Look for a lab that offers a variety test suites. Do they offer suites that including "comprehensive" testing for the Primary, secondary, and trace nutrients? Do the have a suite that includes Buffer pH? Soil Salinity? Do they offer pared down suites that only test for the primary nutrients at a reduced cost? (Although I would recommend a very comprehensive testing suite for the first test done (test primaries, secondaries, trace/micros, salinity and BpH etc. to see where your soil is at/more information makes for better decisions), after which, if your micros and secondary nutrients are within range, you don't need to test them yearly. Run that test every other or third year. Save money and only test the Primary nutrients in the intermediate years.

6. Look at the amenities the lab provides. How easy is it to access, understand and use the portal/site and forms. In addition, some labs will store your yearly results and allow you to run comparisons of individual nutrient changes from one year to the next.

7. Compare fees between labs. (cheapest isn't always best, although don't get fleeced either)

8. Once selected, use the same lab for each subsequent test. It will help reduce variability in results when you make comparisons from year to year.

Quick Summary:
1. Pick an NAPT/PAP lab.
2. Sample correctly.
3. If soil pH is below 7.2, use the Mehlich 3 method.
4. If soil pH is above 7, use the Ammonium Acetate and Olsen methods.
Great Info here!!

Questions:
For #2 - Are you saying even labs on this list are not very equal?

General thought:
Maybe a FWIW section of the lab/s you use or have used and your thoughts on them?


For me, I ordered one sample kit from yard mastery and then I was thinking of going with https://servitechlabs.com/ .. need to follow up with pricing first and see but they do offer:

Image

Which from your above post seems to cover everything I would need and more ... again need to validate price.

I did take a look at Ward, because I think it was what I saw Gman saying he used ?? Correct me if I am wrong ..

But looking at their site and your mention of ease of use, i got completely lost in it haha....


Image

Image

I found the above, but none of that makes any sense to me to fill out .. am I looking in the wrong spot?

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Re: Selecting a Soil Test Laboratory

Post by Ridgerunner »

For #2 - Are you saying even labs on this list are not very equal?
Not at all. I'm saying that the Labs listed on the NAPT/PAP list have met rigorous standards in order to be listed. They've proven their mettle.
Lawn & Garden Soil Analysis
Golf Course and Athletic Turf Analysis

(Fertilizer recommendations given in lbs. per 1,000 sq. ft.)
Nitrate-nitrogen, Phosphorus, Potassium, Sulfur, Calcium, Magnesium, Sodium, Zinc, Iron, Manganese, Copper, Organic matter, Soil pH, Buffer pH, Soluble salts, Cation exchange capacity, Base saturation %
That's a decently comprehensive test. For a cost comparison, Midwest labs offers the S3C for $25.50. Adding the Olsen P test (in case your soil pH is above 7.2) and recommendations adds another $2 for a total of 27.50.
See page 14 for the SC3 test cost and page 16 for the Olsen bicarb test fee:
https://midwestlabs.com/our-industries/fee-schedule/

You'll need to ask @g-man if he is familiar with/has used Ward labs.

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Re: Selecting a Soil Test Laboratory

Post by GoDawgs »

@Ridgerunner that is a great write up. While a lot of it is a foreign language to me, it’s very helpful.

I’m ready to do a soil sample. Do I just pick a company on that list and go with them or can you recommend one to me? Since it’s my first one, I’d like to get the most extensive test. I’d also like to test yearly, with the same company, and be able to view my files on their database.

Do I need to determine my soil PH before I can get a test in order to assure I get the correct type of test?

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Re: Selecting a Soil Test Laboratory

Post by Ridgerunner »

@GoDawgs I'm loathe to recommend a lab to anyone.
I suggest people use a lab listed as a participant on the NAPT/PAP list, as it is some assurance of a lab that does quality work (a lab can't be listed if they haven't successfully complied with the strict requirements for accuracy of results), however a number of labs that people here like to use are not listed (like Waypoint) and that doesn't mean they are not good labs. I recommend you investigate various labs to see if they best meet your requirements.
That being said, I prefer Midwest Labs. They are NAPT/PAP participants, they offer every possible type of agricultural test available for when/if the need arises, they offer individual, stand alone tests, their prices are more than reasonable, and they have a good interactive portal that will track your tests over the years.
If your pH is above 7.2, you will want to use Ammonium Acetate (AA) extractant for the major cations and IMO Olsen for P (phosphorous) although Mehlich 3 P testing can be useful for pH up to 7.5ish. AA will give accurate results for any pH soil, so it can be used for soils with pH below 7 too. For acidic soils, Bray 1 and Bray 2 or Mehlich 3 should be used for P.
For a first test, I suggest you use the most comprehensive test available. At Midwest, that would be the S3C ($25.50 and good for accurate results for any pH for everything except P) and add the Olsen P test from the individual tests (an additional $1) just in case you have a high pH soil.
Midwest also offers Mehlich 3 testing which is an alternative for lower pH (7 or lower). See their site, however I don't think their M3 suites are as comprehensive as the S3C. A belt and suspenders approach would be to combine the S3C (AA and Bray 1 and 2 P -25.50) with Olsen P -$1) and the S3M (Mehlich 3 -$10.50) for a total of $37, if your wallet can stand it. That way you're covered for the comprehensive initial/baseline test and you can decide where you want to go from there for future testing.
https://midwestlabs.com/our-industries/fee-schedule/
Hope that helps.

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Re: Selecting a Soil Test Laboratory

Post by GoDawgs »

@Ridgerunner yes that helps tremendously. I’m knee deep in your other posts on the topic so I’m sure I will have some more questions on the topic but I’ll try and get them all together instead of asking 10 questions separately. Thank you for taking the time to share your wealth of knowledge.

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Re: Selecting a Soil Test Laboratory

Post by jeffjunstrom »

Does proximity of lab have any effect? Analysis is analysis, but is it better, all else being equal, to use a local lab who may be better versed in the issues of the region? I'm in Pittsburgh, and I'm torn between Midwest and Waypoint. I used my local Penn State office last year, and wasn't pleased with them. Waypoint has an office in the state (albeit on the other side of the state), while Midwest is located in Nebraska. Does that matter at all?

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Re: Selecting a Soil Test Laboratory

Post by g-man »

It only matters if you can drive to deliver the soil samples and save $ over shipping via USPS.

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Re: Selecting a Soil Test Laboratory

Post by cvaline »

Great resource. Thank you!

http://www.al-labs-west.com/fee-schedul ... 20Analysis
Is the S3C test the most appropriate for a first-time soil test? Any other things I should consider?

Also, what's the easiest way to see the testing method? I'm not sure I see that as a choice to select on their website.

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Re: Selecting a Soil Test Laboratory

Post by Ridgerunner »

I don't see where they identify the extract (testing method of Ca, Mg and K for the S3C (S1B actually) either. I'd call them and ask if they use ammonium acetate for Ca, Mg and K. Also ask them if the report will include the results for BOTH Bray1 and Olsen testing for P. If so, then you will get useful information no mater what your soil pH is.
Yes, the S3C would be good for the initial testing as it will provide results for all of the nutrients important to turf/plant health plus a salt index. It would provide a baseline to compare too in the future, but unless a level is way outside recommended levels, you can use one of the less comprehensive (and less expensive) tests for testing in future years.

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Re: Selecting a Soil Test Laboratory

Post by SCGrassMan »

Waypoint is awesome, and its who I use. I think it was Ware who originally recommended them to me, but I'm not sure. I do the S3M test on 4 areas of my yard, front, back, sidewalk, and side yard, and pull 12 cores from all over for each one. I make sure to get some soil from problem areas, as well as some super healthy areas to balance it out.
2019 Lawn Journal:
viewtopic.php?f=26&t=7338
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We don't speak of this year.
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viewtopic.php?f=26&t=26593

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Re: Selecting a Soil Test Laboratory

Post by Ridgerunner »

SCGrassMan wrote:
Wed Apr 07, 2021 10:57 am
Waypoint is awesome, and its who I use. I think it was Ware who originally recommended them to me, but I'm not sure. I do the S3M test on 4 areas of my yard, front, back, sidewalk, and side yard, and pull 12 cores from all over for each one. I make sure to get some soil from problem areas, as well as some super healthy areas to balance it out.
You are in the Southeast where most soils are acidic (low pH) and the Mehlich series of tests will provide useful results for low pH soils. Large areas of Ca have high pH soils and results for Mehlich will not provide the most useful results. Waypoint is a decent Lab, but they are not NAPT/PAP and A&L Western is.

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Re: Selecting a Soil Test Laboratory

Post by Duxwig »

Is it wise to invest in some type of probe? They seem costly. Yardmastery kit comes with them - or bunk?

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Re: Selecting a Soil Test Laboratory

Post by Ridgerunner »

Reliable soil testing is directly related to proper sampling. The more soil plugs, the better. Around 3-4 plugs/samples per thousand square feet is recommended. A soil probe certainly isn't necessary, but it makes pulling samples much faster and makes it easier to take the number or recommended plugs. Whatever tool you use, probe, shovel, spade, trowel or bulb planter make sure that it is made of a material that wont contaminate the soil sample. I suggest stainless steel. Never use galvanized or copper. Look at it this way: If you had to put in twenty screws, a screwdriver will do the job, but wouldn't you rather use a power driver? The cost/benefit analysis is personal, but for me $25 - 50 is worth the time and effort savings.

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