# Bassadict69's Soil Test Results...NEED HELP!



## bassadict69 (Apr 2, 2018)

I am finally getting around to posting my soil test results...it doesn't look good! Sample was a mix of about 15 spots in my backyard, all taken 3-4 inches deep. Covered area is about 12K sq ft.

Help with recommendations?

pH (1:1 Water) 5.16 Very Low
Phosphorus, ppm 38.77 High
Potassium, ppm 72.10 Medium
Calcium, ppm 209.34 Very Low
Magnesium, ppm 46.04 Very Low
Sodium, ppm 12.24 Optimum
Sulfur, ppm 11.60 Low
Copper, ppm 0.64 High
Zinc, ppm 1.56 Medium

Soil Texture:
very fine sandy loam


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## Greendoc (Mar 24, 2018)

That is not that bad. Bad is when you have astronomical levels of Sodium and Magnesium in a clay soil with pH over 7.5. Some Dolomite lime is needed to bring this one back in range. Another thing in your favor is the sand. Because it is sand, small amounts of Dolomite will have a rather large effect on the soil composition.


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## bassadict69 (Apr 2, 2018)

Last sample was in 2016 and it was 5.8 and I did 3 applications of lime over the course of that summer...I sure didn't expect it to be lower!


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## Greendoc (Mar 24, 2018)

Rain, watering and fertilizer will do that. Your conditions suggest that Centipede is doable in your location. My favorite grass, next to Tifgrand is Centipede kept at 5/8" with a reel.


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## bassadict69 (Apr 2, 2018)

Too shady I believe...We still have quite a few trees.


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## Ridgerunner (May 16, 2017)

bassadict69 said:


> I am finally getting around to posting my soil test results...it doesn't look good! Sample was a mix of about 15 spots in my backyard, all taken 3-4 inches deep. Covered area is about 12K sq ft.
> 
> Help with recommendations?
> 
> ...


Would need to know what tests were used to extract each of those numbers.


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## Greendoc (Mar 24, 2018)

Mehlich III and Bray solution extractions are the right procedures for neutral or acidic soils to determine P. Olsen extractions are what are used for alkaline soils. Acid soils are easier to test and interpret. I have issues with interpretation on alkaline soils because actual availability and response to detected nutrients does not agree. A pH over 7.0 or under 6.0 means there will be issues with nutrient availability. Any doubts are erased when soil pH is corrected to below 7.0. and over 6.0 As for micronutrients, normally, those are extracted with a chelating agent. What I do is first look at the soil test, then look for symptoms or poor growth, then see if they correspond. I think it is well worth it to aggressively correct pH. Lime is cheaper than fertilizer. Once pH is corrected, you will find that a small amount of fertilizer produces a large response.


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## Txag12 (Apr 22, 2018)

You're going to be battling the CEC ratio of sand which is very little so you'll have a lot of nutrient leaching. I'd do what @Greendoc suggested and hit it with lime. For that size I'd start with 200# of lime and see what happens.

On those three applications of like, how much was actually applied during each application?


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## Greendoc (Mar 24, 2018)

I love sand. 200 lb of lime is a good start, followed by another 200 applied at monthly intervals. Another way to do it is with a single 1000 lb application in the winter.


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## bassadict69 (Apr 2, 2018)

Mehlich III was listed, if that is what was being asked.

Lime was applied at a rate of 9lbs/k in 2016...


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## Ridgerunner (May 16, 2017)

You have a very low CEC soil. Probably between 3 and 4, closer to 3. That means the soil will not hold much in the way of Base Cation nutrients, deplete fairly rapidly and constantly tend to become acidic.. A sand soil will also leach nutrients quickly below the root zone. You will want to fertilize/amend regularly to maintain an adequate supply of nitrogen and potassium and a desired pH. Using potassium sulfate should raise, or at least maintain your sulfur levels. 
Your test doesn't provide Al. (not usually an issue in the S.E,) or Mn. levels. Either of which can become toxic at low pH. You haven't identified the lab you used, but most labs retain the soil samples for 4 weeks. If the lab still has your sample, I would suggest you ask them to run a buffer pH test (if possible: Adams-Evans or Moore-Sikora rather than SMP) to determine the best estimate of the lime needed to raise your soil pH. Otherwise you will be playing a game of Battleship.


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## bassadict69 (Apr 2, 2018)

LSU-Ag center did the tests...I will call Monday on my day off and ask about it.

Suggestions on appropriate fertilizer?


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## Ridgerunner (May 16, 2017)

> Suggestions on appropriate fertilizer?


Seldom, if ever is there one perfect fertilizer. Usually we need to alternatively mix and match to supply the nutrients needed for our particular situation.
Your soil has shortages in Ca and Mg and is medium to low in K and S.
You should wait on the Buffer pH results and Lime Recommendation before deciding on the best sources for addressing those nutrients. In preparation, you could check on the availability and cost of potassium sulfate, K-mag (Sul-Po-Mag or the like), calcitic lime, dolomitic lime, a 10-0-10, a 4-1-2 and a 34-0-0.
In the meantime, you can/should follow the recommended N application schedule for St. A. Whatever that is (sorry, I'm a cool season person).


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## bassadict69 (Apr 2, 2018)

Found this info on my sample results also...

Crop st. augustine

Units: lb/1000 sq. ft.
Nitrogen See Sheet
Phosphate 0
Potash 1.05

Expected pH / Acre with adding Lime
1 Ton
6.70
Optimum


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## Ridgerunner (May 16, 2017)

The values you posted as ppm are correct?
How about posting an image of the actual test.
That they made a lime/pH correlation usually indicates that a Buffer pH test was performed, but not always.


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## bassadict69 (Apr 2, 2018)




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## bassadict69 (Apr 2, 2018)




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## Ridgerunner (May 16, 2017)

I had hoped to have my tests up and done a write-up explaining the process, but I've been lazy.
Anyway:
First up is pH. LSU recommends 1T/acre or 45 lbs/M (seems a bit high considering your probable CEC, but they are in a better position than I) to raise pH to 6.7. If you prefer not to raise quite that high, you could apply slightly less (40-43), Although it is safe to apply 50 lbs/M at one time, the consensus is to apply lime at a rate of 25 lbs/M in the Spring and then again in the Fall. It all depends on what your threshold level is for poorer performing turf is during the time the lime is working. You have two basic choices calcitic lime (adds calcium only) or dolomitic lime (adds both Calcium and Magnesium). If you decide to go a different route (Calcitic lime or a fast acting lime), you will need to adjust the rate and timing of application and will need to find a separate source for Magnesium. As your Magnesium and Calcium levels are "low" you don't want to add more Calcium at the expense of Magnesium, so dolomitic lime would be a good choice although dolomitic is slower to work. Dolomitic would be a good easy choice.
I'll address the rest later this weekend if you want to continue.
EDIT: thanks for the image, that rang a bell. I think LSU does a lime titration test rather than a Buffer pH, that'll work.


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## bassadict69 (Apr 2, 2018)

/M is the same as /K?

Thanks for the simple explanation...I will begin shopping for dolomitic lime this weekend...any suggested brands?

I would definitely like to continue as I am completely lost...please address the rest at your convenience and thanks again!


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## Ridgerunner (May 16, 2017)

Yes, M=k.
I would encourage you to ask LSU what they would recommend, they should be familiar with the general products available in your local and hopefully where to find it.
Brand doesn't matter. 
Unless you have a drop spreader, you will want pelleted/prilled.
I would look for a product with at least 100% passing through a 40 mesh with 85% passing a 60 mesh and 40-50% passing 100 mesh.
Easier to ask LSU for guidance, unless someone here can give you a heads-up.


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## bassadict69 (Apr 2, 2018)

Thank you sir! I will head down to the local LSU Ag extension tomorrow...


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## Ridgerunner (May 16, 2017)

Sorry for the cop-out, but I think seeking input from the LSU Ext. is a better route than trying to advise you via the forum. There are a couple of reasons for the referral:
1. We don't know whether LSU's lime recommendation is based on the common CCE value of Ag-lime readily available in Louisiana or on a standard 100 CCE basis nor do we know if the rec is to adjust pH to a depth of 6" or greater. In either case, you would need to calculate for adjustment.
2. Once that adjustment is made, you would need to adjust for the particular product available to you. Although the major national brands are very consistent in product content, some products are not available in certain regions of the country without special order $$$ or they may need to be supplemented to get the Ca and Mg needed.. Some products are so finely ground (fast acting) that application rates and timing rates need to be adjusted to compensate and avoid/reduce detrimental effects.
I could have bored you with MY explanation, but it would be just a regurgitation of the articles I've read (albeit, it would have been a compilation of information from a number of different sources  ).
Or I could post a bunch of links on the topic that no one would read. 
My compromise: This is a good easy read that hits the highlights most of the variables:
https://extension.psu.edu/liming-turfgrass-areas


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## Ridgerunner (May 16, 2017)

Moving on from pH, Ca and Mg.
Based on a Mehlich 3 test, although the unit values are not labeled, I'm pretty confident the numbers reported are ppm and not lbs/acre. (When you visit the Ext to get their input on lime, you can verify this too)
Phosphorous:
Recommended range for Mehlich 3 reported phosphorous values is 26-54 ppm (see https://thelawnforum.com/viewtopic.php?f=22&t=1088 for the M3 chart)
Reported as 38.77.
IMO, that's a good value to maintain.
To convert ppm to lbs per acre furrow slice (the lbs in the top 6" of soil), multiply by 2.
38.77 ppm = 77.5 lbs
Normally, we might want to adjust/reduce this to the 4" depth, however in a sand soil, it's very likely your turf roots have driven deeper than that top 4".
To convert lbs/acre to lbs per M (thousand sq ft), divide by 43.5.
77.5 lbs/acre = 1.78 lbs/M at 6" depth (about 1.2 lbs/M at 4")

Potassium: 
Reported value of K is 72.10
Recommended range for Mehlich 3 reported potassium values for sand soil is 60-120 ppm. (see same above link for M3 chart)
Conversion factors/formulas are the same as for phosphorous.
That's 3.3lbs/M at the 6" depth (2.2lbs at the 4" depth)

Turf grass will take up/use between 0.2 and 0.25 lbs/M of Phosphorous and between 0.5 and 0.9 lbs/M of Potassium for every 1 lbs/M of Nitrogen. If you apply 4lbs/M of N over the season, you can expect the turf to take between 0.8 and 1 lb/M of P and between 2 and 3.6 lbs/M of K from the soil over the growing season. If you apply 5 lbs/M of N over the season, you can expect the turf to take between 1 and 1.25 lbs/M of P and 2.5 and 4.5 lbs/M of K over the growing season.
The objective is to supply the turf with the N, P and K needed for healthy, attractive growth from some combination of fertilizing and the nutrients already held in the soil.
A soil test reports the amount of nutrients already in the soil. Rather than think of those values as nutrients to be used or nutrients that don't need to be supplied by fertilizing, think of them as an insurance policy or as nutrients in a bank account for emergencies. You have 1.78 lbs/M at 6" depth and 3.3lbs/M at the 6" depth in the "bank." IMO, not bad. So:
Decide how much N you will be applying for the season (will vary depending on grass type and desired level of turf performance- e.g. color, growth rate, desired mowing frequency, etc.) Multiply the total amount of N you will apply by the factors for P and K given above to determine the amount of P and K fertilizer needed for the growing season.
FYI, the P and K amounts listed on a fertilizer bag are not elemental values. P content on a fertilizer bag are for a P2O5 equivalent and K content is for K2O. You will need to convert the P and K you calculated as needed for the growing season so that you know how much P2O5 (what;'s listed on the bag) and K2O (what's listed on the bag) you need to apply for the year.
For examle:
Applying 5 lbs/M of nitrogen would require 1 lb/M of P (5 X 0.2) and 3.75 lbs/M of K.
Therefore, we will need to apply 2.3 lbs/M of P2O5 (1 lb of P times conversion factor of 2.3 = lbs of P2O5) and 4.5 lbs/M of K2O (3.75 lbs of K times conversion factor of 1.2 = lbs of K2O).
If we are short on the amount of P and/or K we applied, the turf plant can make up the shortage by taking some out of the "bank." If we applied too much P and or K, the amount in the "bank" should increase. (There are some finer points to be made here, but it's sufficient to advise against over "banking".) Next years soil test will reveal what happened. If the values drop by more than 10% from this year's values ("the bank account"), we didn't apply enough fertilizer and should up it a bit (e'g. use 0.25 instead of 0.2 for calculating next year P fertilizing rate). If next year's test values ("bank account") increase by more than 10%, we should slightly reduce next year's P and/or K application.


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## bassadict69 (Apr 2, 2018)

Crap! I have a headache now! Haha! Thanks for the detailed explanation... I will post back tomorrow what I find out at the Ag office.


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## bassadict69 (Apr 2, 2018)

LSU has recommended 13.4 pounds/k of dolomitic lime. Sounds a little low, I was expecting much more.


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## bassadict69 (Apr 2, 2018)

I have read the above dozens of times and it is still over my head! Anyone care to put that into laymens terms? What fertilizer would YOU use?

My main goal is as much growth and spreading as I can get...if I need to mow every 2-3 days, that is fine!


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## Ridgerunner (May 16, 2017)

Some great possibilities in this thread:
https://thelawnforum.com/viewtopic.php?f=3&t=2940
That Lesco 21-4-11 is great and 10-10-10 will work.
or one of the X-0-0s if you don't mind depleting the soil P&K.


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