# Soil analysis help



## nortex (Jul 18, 2020)

Hi,

I'm new to the forum, and I just got my first soil analysis done. I'm hoping for some pointers on how to improve my numbers, and ultimately my grass. Some context: I'm in my second summer of a new construction home in the Houston area. The grass is a hybrid bermuda variety, probably Tif 419, although I don't know that for sure. I typically follow the local lawn guru's (Randy Lemmon) recommendations of applying a 3-1-2 ratio slow release fertilizer at bag rate twice per year, plus a winterizing fertilizer in late fall. The last application was 2-3 weeks before I took the soil sample, and we had several inches of rain between fertilizing and taking the soil sample.

The grass looks "ok", but I'm not quite happy with the density, and I have some areas that tend to look a little yellow, and not as full/vigorous as the rest of the lawn. You can see it closest to the camera in the bottom picture. The swale seems to be the worst offender. It probably has very little topsoil - maybe that's why. I have also noticed some light green new growth/chlorosis in several areas. I would have thought iron deficiency, but the report shows plenty of iron. Maybe the high pH is to blame. You can see it in the first picture of the grass.

Speaking of pH, the soil test results show moderately alkaline soil (pH 7.8 7.9) with a very high calcium content (7441 ppm  ). I was surprised at how high both these numbers were. Is it even feasible to bring down the pH at a reasonable cost/effort, considering the high calcium content? I'd like my lawn to look nice, but I'm not interested in spending a fortune in the process. I'm not sure about the best course of action here. Any suggestions would be appreciated.

P was low at 30 ppm, maybe because I didn't apply starter fertilizer after moving in? The Zinc was also low.

K was very high at 448ppm. Should I stop using 15-5-10 as my go-to fertilizer for a while, or will this leech out with rain/irrigation? Could the relatively recent application of 15-5-10 have thrown off the results?

My plan is to use granular starter fertilizer (24-25-4) at a rate of .5lbs of N/k, two weeks apart, in order to bring up the P. The N is 6% slow release. In two applications I will have applied 1lb of P2O5/k, which is about what the soil analysis recommends. Does this sound like a reasonable approach? Will I burn my grass by applying this in the summer, or am I safe at that rate, assuming I water it in properly? The temperature forecast is actually reasonable for the next week, with a high of about 90F.

Once I've applied the required P, can I maintain it by continuing with 15-5-10, or will this be a constant battle to keep the P sufficiently high?

The report also recommends using a micronutrient fertilizer to improve Zn, without adding manganese or copper. Are there any affordable options for achieving this?

Lastly, since it might be relevant, I leveled my lawn with 6 yards of masonry sand right after taking the soil sample, but before getting the results. I fertilized with Nitro-Phos 19-4-10 at .5lbs N/k to encourage growth two weeks ago. In other words, I've already added .5N, .1P, and .26K /k since the soil analysis was done. You can still see the sand in the low spots in the pictures. Hopefully it fills in soon.

Thanks!


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## rjw0283 (May 11, 2020)

@nortex I can't provide much feedback on lowering PH, (I have low PH) But applying N twice a year isn't going to give you the N it needs. I have a soil with extremely low K, I apply it every 2 weeks, it'll leach away. 
I only use fast release nitrogen, it'll be fine! Put on dry grass, try to time it before rain, or use irrigation (I do this @ night before the sun goes down.) I put about .7- 1 lb of N down per month (Around .40lbs every 2 weeks UREA via foliar) 
If your scared of burning your yard do small amounts but do it more frequently (every 2 weeks or so) Every yard is different, and that works for me. Get some Phos and Nitrogen. Hopefully someone chimes in with high PH.


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## Virginiagal (Apr 24, 2017)

If you haven't seen this Welcome to the Warm Season Forum, there are useful links in here:
https://thelawnforum.com/viewtopic.php?t=1077
Since we don't know what lab or what kind of testing agents were used, I doubt that we have much to say about the soil test results. Starter fertilizer would give you phosphorus and your plan seems reasonable (I'm a cool season person so not too familiar with fertilizing Bermuda though I know it's fertilized during the summer). Water it in after applying. Don't worry about too much K. it's fine. Lowering pH is sometimes just not possible if the soil is calcareous. There is a vinegar test that can be done to see if it is. Foliar iron can be used to improve the grass color if pH can't be lowered.


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## Ridgerunner (May 16, 2017)

Hi @Virginiagal It appears to be TAMU. They use M3.


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## Virginiagal (Apr 24, 2017)

Hi @Ridgerunner . Glad you recognize the lab. Maybe you'd like to tackle some of Nortex's questions, like about zinc? @nortex, phosphorus is slow to move through the soil profile. Once you bring it up, it shouldn't readily leech away. Of course, rain runoff is something to avoid. Good to put it down before a gentle rain or some irrigation, but not before a downpour.


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## nortex (Jul 18, 2020)

Thanks all!

@Ridgerunner, TAMU is correct, and you're right that they use M3, according to their website: http://soiltesting.tamu.edu/webpages/swftlmethods1209.html

I'll go with the starter fertilizer (Scott's Starter 24-25-4) to address the phosphorous level, then re-test next year to check if it helped. I'm curious to see how much of an effect the added phosphorous will have. In a sense I'm happy that the soil test came back showing some deficiencies, especially "low hanging fruit" like phosphorous. On the other hand it's disappointing that the pH is so high, since I suspect that's a bigger issue, and not one I can easily address... @Virginiagal , I'll look into the vinegar test. I wish I would have saved a bit of the soil I sent off to A&M...

The Zinc is still an issue, but I'm not sure how critical that is..?


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## Virginiagal (Apr 24, 2017)

Here's something I found that looks fairly reliable on zinc:
http://documents.crinet.com/AgSource-Cooperative-Services/Turf/F-07054-14-GIS-Tech-Zinc.pdf
One thing of concern I'm reading is that phosphorus fertilizer can increase a zinc deficiency. So maybe you should look into addressing it. Perhaps your local agriculture extension office can give some advice. Ridgerunner may have some insight.

You can use any of your native soil to do the vinegar test.


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## Ridgerunner (May 16, 2017)

Recommended sufficiency levels for Zn are >1-2 ppm.
Turf is very efficient at extracting the small amounts of micro-nutrients it needs. Are you seeing any of the signs (like yellowing) that could be caused by a Zn deficiency, if not, let it ride. If you are seeing signs or you just want to raise levels, you'll want to source a chealated form for soil surface application. You'll need to shop around (Site One or Carbon Earth may have a product). For foliar application, Zn sulfate should work, but that will need to be applied on a regular bases just like one does Fe. If leaving clippings is an option, then do mulch.
FYI 2lbs of Zn/acre = 1 ppm. Suggest you not attempt to raise Zn more than 1 ppm per season.

With a pH of 7.9, you should use a lab that uses ammonium acetate and Olsen testing in the future for more useful results.


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## nortex (Jul 18, 2020)

@Virginiagal , that's an interesting article. I do have some yellowing of new growth, which could be either zinc or iron. I have some ironite left over from last year, I'll try to sprinkle some and see if it helps. If not, I guess that might indicate that the zinc is more likely to be the problem.

@Ridgerunner , based on the article above, it looks like Zn is practically insoluble in a pH of 7.9 (.000000412ppm @pH of 8). Does this mean that adding some sort of granular Zn supplement won't make any difference? I already have .21ppm Zn, and if only .000000412ppm is soluble, then it seems I won't gain anything by increasing my levels? The article also states that "However, a 1.0 ppm zinc level would definitely be deficient on an alkaline sand soil with organic matter less than 1%.". I guess I don't understand why the ppm makes much of a difference, if it's not soluble and therefore isn't available to the grass anyway? I must be missing something here. I'm also surprised that the soil test report says the critical level for zinc is .27ppm, not 1ppm as you and others mentioned.

I'll keep the high pH in mind for my next soil test, and try to find a lab that's better for alkaline soil.

I put down the first application of starter fertilizer last night. Hoping the added P will help. I'll sprinkle some ironite around my spots with pale grass and see if there's any improvement, but I realize that the high pH will limit the effect of iron as well...


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## g-man (Jun 15, 2017)

You should do FAS or a chelated iron with a high pH. I would not worry about zinc. Try the FAS first. Check the soil remediation guide for other P products you can use.


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## Ridgerunner (May 16, 2017)

That's an excellent article @Virginiagal posted.
pH is important due to the chemical reactions that occur (or don't occur) because of the pH. In high pH soils, Cation nutrients are more likely to combine with Anions to make forms of the nutrient that plants can't use. (In low pH soils, the nutrients can be in forms that are so available that they can become detrimental, even toxic to plants- but that is extraneous information for your situation.)
In high pH soils a work around, to avoid nutrients from forming bonds that make them unavailable, is chelation. Surface applying chelated nutrients (in this case Zn, more costly, but longer lasting) will help make the nutrient available for plant uptake. Nutrients held in humate CEC is chelated, but citric acid is also a chelator (search posts by greendoc on using citric acid to chelate nutrients). In the alternative, the soil can be bypassed and nutrients can be applied to the leaf (cheaper, but more effort).
TAMU marches to their own drummer and to be honest, I've never understood their tune. I would recommend that you not start addressing micros (Zn) until you get level conformation through a different lab.


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