# GA Fescue Man's Soil Test (2019)



## GA_Fescue_Man (Jan 7, 2019)

Hope things are going well. I just received my soil test report from Midwest Labs and wanted to get some feedback. I live in metro Atlanta and like most soils in Georgia (GA), has a high clay content. I have TTTF and I have attached my soil test for reference. Thanks for taking a look at it.

*Here are my number ranges that I am trying to work towards over the next couple of years. Hats off to @Ridgerunner for such a great thread on soils! The P,K,Ca, & Mg numbers have been tweaked some.*

PH - Trying to keep this around 6.5

Available (P) Phosphorous - 60 to 80 PPM
Exchangeable (K) Potassium - 120 to 510 PPM
Exchangeable (Ca) Calcium - 700 to 1300 PPM
Exchangeable (Mg) Magnesium - 140 to 270 PPM

Base Saturation Percentages
CA - 65 to 80%
MG - 10 to 20%
K - 3 to 8%
NA - Less than 3%
H+ - 10 to 20%

CA to MG Ratio - Trying to keep this around 6:1 to 8:1
K to MG Ratio - Trying to keep this around 0.7:1 to 1:1

*Here are my observations and questions.*

1. The CEC is at 5.6 for the front & 5.0 for the back. That feels like a lower level for a clay based soil in GA. Thoughts? My organic matter seems to be at decent level at about 3.8%. Just thinking about my plants ability to take up the nutrients that I apply. If I increase the OM % over time, will this increase the CEC as well?

2. PH is a little low in the front yard (6.1) and definitely low in the back yard (5.5). I was thinking to apply dolomitic lime to raise PH and MG levels? Should I use calcitic lime? How many lbs. per K? Any recommendation on lime brand?

3. The P & K are low as well. I will using an Air8 & RGS combo application 5 times per year to help with some compaction in my clay soil. Over time, will this combination help "free up" some of the phosphorous that is bound up in the soil? I am currently using a balanced 14-4-24 fert with micronutrients that may help with some of the P & K deficiencies over time.

4. Just any other recommendations or observations that you see from the test that can help me manage things long term?


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## Ridgerunner (May 16, 2017)

> 1. The CEC is at 5.6 for the front & 5.0 for the back. That feels like a lower level for a clay based soil in GA. Thoughts?


Generally, clays have a high CEC (numerous negative charges resulting in CEC between 20-40ish). However, as clay weathers it loses more and more negative sites. Some regions, like the Piedmont soil regions of Ga, the Carolina and Virginia are known for their weathered low CEC soil. It is very likely you have weathered clay soil. Although the texture of your soil is clay, its holding capacity for cation nutrients, CEC, is more similar to a sandy soil-low. Keep your CEC in mind as you begin to try to adjust nutrients. You don't have a lot of storage space.


> My organic matter seems to be at decent level at about 3.8%. Just thinking about my plants ability to take up the nutrients that I apply. If I increase the OM % over time, will this increase the CEC as well?


That's actually pretty high OM% for a southern soil. Yes. once OM has decayed (estimates are 2-10 years or more) into stable humic substance, it will contribute to the CEC. Stable humic substances have a CEC >100. Some estimates are that every 1% of OM will add 2 meq to CEC. I think that is extremely optimistic.


> PH - Trying to keep this around 6.5


 \You can use a combination of calcitic and dolomitic lime to attempt to adjust the quantity and ratio of Ca and Mg in your soil. Keep your expectations in check and keep the limitations of your CEC in mind. Getting your pH to 6.5-7.2 will improve P availability.


> CA to MG Ratio - Trying to keep this around 6:1 to 8:1


A range between 6-8:1 is probably wide enough to be doable. At best, it's a game of whack a mole. Adding one nutrient will knock some of the other nutrients (Ca, Mg. and K) out. See above about using calcitic and dolomitic lime for adjusting.


> K to MG Ratio - Trying to keep this around 0.7:1 to 1:1


I believe that's a bridge too far. You may be able to refine it over years and practice, but the variables and soil dynamics are not very conducive to such refined targets. I would caution you to not overshoot. Studies do report detrimental effects when K levels exceed Mg levels in the K:Mg ratio. Best to target a Mg:K ratio of 3:1. IMO, the benefit doesn't outweigh the risk. I doubt that you would see any difference in the turf with a Mg:K ratio of 5:1.


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## GA_Fescue_Man (Jan 7, 2019)

@Ridgerunner Great insight. Thanks so much for the reply. I need to get my PH in line first and then start working on other adjustments over time. I really appreciate it.


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