Longtee81 - 2021 Soil Test

[Longtee81]

First time soil test.

My yard is 8000SF total ~ 5000 SF in front/sides and 3000 SF in back.
When our house was built ~15 years ago, the foundation heavy soil was spread across our front and side yard. The back yard, which had a lot of trees and brush, was left undisturbed. The front yard is challenging to grow things in (trees seem to struggle and grow realy slow, and any holes dug would remain saturated for days, whereas the backyard is a dream. Nice chocolate loam, drains well, easy to dig in and plants/trees establish quickly and grow fast.

We brought in about 1-2 inches of topsoil, graded and then installed KBG sod on top of the soil. Over the years, I have always kept up on mowing and the lawn regularly and the yard has been mostly weed free as it was kept around 3.5 to 4 inches.

In the last two years, I have been more involved and in the Fall of 2019, I started reel mowing.
In the fall of 2020, I killed off my front yard, brought in a top soil mix (10% sand - ~10% compost - and the remainder topsoil) and topdressed the yard with about 1/2 inches of the soil before planting some new KBG varieties (50% Mazama, 30% Bewitched, 20% Award)

I irrigate quite regularly, and did much more in the front yard this year due to the renovation and new KBG I was growing in, but much less in the back yard this past year. The PH of my irrigation water is 9.2, so I'm wondering how much that contributes to my alkaline soil numbers. I have also probably abused starter fertilizer as I was applying that for my seed/overseed projects as well as a spring time fertilizer in past years.

I've included both the front and back yard soil test results for comparison, but I'm interested mostly in the front yard as that has always lagged behind my back yard in terms of color, vigor, and overall look.

I did a lot of Urea sprays on the front yard last fall for the new grass, and didn't keep up on a balance program as much as I typically would.
I'm interested in topdressing to take care of some issues I have in the back yard with bumps, as well as the front renovated yard.

I see all of the internet Youtubers using sand, but I'm terrified of introducing layers and not wanting to a life long commitment to aeration and sand. I would like to use soil, but and concerned over introducing Poa A and Poa T into my lawn, so any tips on the best soil type to gradually level would be greatly appreciated.

Thanks for any input and any advice regarding my soil results!

[MorpheusPA]

If you're going to topdress, use a soil that matches your topsoil as well as you can. In this case, I'd recommend doing the jar test (search the site for that). I have a guess that you have a fairly heavy soil with a lot of silt, but there may be more clay than I think there is initially. Most landscapers will be able to sell you a topsoil that's pretty decent, and even if it's simply a silty loam, that's fine. Pure sand would be a horrible mistake, as would anything with a high level of organics.

Since this is your first rodeo, I'll go line by line on the important stuff. It's obvious why your front yard lags. It'll take some time to catch that up due to the pH, but it can be done.

Exchange Capacity 19.6, 12.0: How much the soil holds in terms of resources. Here, the answer is, "A fair bit and a middling amount, respectively." The first answer is a little overinflated because there's excess calcium in your soil, pushing the number up, so I'm mentally turning the answer down to about 14 when I make recommendations. There's no right answer here, my soil's around 15 as well. All numbers are good numbers.

pH 8.4, 7.1: Very high and high. While not the most useful, it does tell us that grass will grow just fine, but you probably shouldn't expect the best green color out of your lawn (it requires a lot of iron, which isn't available at high pH over about 6.8). It also means that, unless you're specifically told to, never lime this lawn. But we're not going to do anything specific to try to bring it down either, because that's a waste.

Organic matter: 4-ish: Good! It's a nice place to start. Certainly mulch mow, mow in all your fall leaves, and maybe think about feeding organically if you want to, but this is a good number to have.

Sulfur 20-ish: Normal. There's no right number for this and anything from about 8 to about 100 is just fine.

Phosphorus 100, 150: Quite low. The targets here would be 350 and 250 respectively (my set targets change with the pH, and with a pH over 8, they go way up as P becomes far less accessible as the pH rises). Normally, we'd use a starter fertilizer for this...but not this time. Because of another problem below, let's go with a balanced fertilizer, one where all three numbers are the same like 10-10-10 or 20-20-20. If it's 12-12-12 or 15-15-15, that's wonderful. It's all the same. Get the cheapest per unit price (where the fertilizer unit is cheapest). You'll do this through 2021 and 2022. This looks like the limiting factor in the front (and back, to a lesser extent). It has little access to phosphorus, and yet another reason I'm recommending additional Milorganite feeding (rich in phosphorus) through the year.

Calcium 80, 76%: High, which is as expected with a higher pH. This is fine, but we don't want to add to it. Grass really doesn't care.

Magnesium 15, 17%: It looks optimal and is actually a bit high (calcium is pushing it down a little). So we definitely don't want to add any. The grass won't care.

Potassium 1.4, 1.6%: A bit low, and it shows in the numbers per acre as well. This is why I recommended the balanced fertilizer, to add some potassium at the same time. The shortage isn't severe, but some additional will help. This is your second limiting factor, but it's minor.

Trace Elements:
Zinc is low for your pH and I'm not thrilled with your copper either. Iron is also rather low. However, read the Micronutrient Application Guide and let me know how comfortable you would be with adding these. If you are, I've added the recommendations below. If not, just skip them. Note that the iron will have some effect in the back, but probably not so much in the front--the pH is just too high for it to show very much at all.
For zinc, you'll need zinc sulfate. For copper, copper sulfate.

If you want to simply drop the Milorganite for iron and not use the zinc and copper, that's fine--it'll supply additional feeding for the lawn as well, organically, some iron, and it has trace zinc and copper in it to begin with. Not enough to influence the test, really, but everything helps.

Recommendations:

May 1: Apply 3 Tbsp zinc sulfate and 2 Tbsp copper sulfate in Milorganite carrier using the Micronutrient Application Guide.

Memorial Day (May 25th or so) Apply balanced fertilizer at the bag rate (or ask if unsure).

August 15: Apply 3 Tbsp zinc sulfate and 2 Tbsp copper sulfate in Milorganite carrier using the Micronutrient Application Guide.

September 1: Apply balanced fertilizer at the bag rate (or ask if unsure).

October 1: Apply balanced fertilizer at the bag rate (or ask if unsure). FRONT ONLY: Apply 3 Tbsp zinc sulfate and 2 Tbsp copper sulfate in Milorganite carrier using the Micronutrient Application Guide. IN BACK: Apply plain Milorganite for iron and additional feeding if desired.

[andy10917]

I see all of the internet Youtubers using sand, but I'm terrified of introducing layers and not wanting to a life long commitment to aeration and sand.

Did you pay attention to where the Youtubers were living/located? Using sand is a technique that is used with (mostly) Bermuda lawns in the South. There are some northern folks that blindly copy it, but it's not valid in the North.

[MorpheusPA]

I've remained unsure it's all that valid for Bermuda lawns unless the soil is sandy, but that's quite another story.

[Longtee81]

Thank you MorpheusPA for the super detailed response! I really appreciate all of your time spent reviewing and responding to my soil test!

I think that all makes sense to me, I will have to re-read it a few more times to fully process.

I'm going to review the Micronutrient Application Guide and other guidance on the site. Can you please confirm the rates you recommend are at a per 1000sf application rate?

One thing I need clarification on is the ability to use iron. I understand the PH impacts this, but would this still be an issue for liquid iron sprays that absorb through the leaf?

Thanks!

[Longtee81]

I see all of the internet Youtubers using sand, but I'm terrified of introducing layers and not wanting to a life long commitment to aeration and sand.

Did you pay attention to where the Youtubers were living/located? Using sand is a technique that is used with (mostly) Bermuda lawns in the South. There are some northern folks that blindly copy it, but it's not valid in the North.

From what I understand, based on the university studies, etc. is that sand is meant for the south or for golf courses in the north who are committed to topdressing for life. There appear to be more and more people leveling and topdressing for sand in the north, but I agree they are just copying what they see others do and probably not thinking it through. Thanks for reassuring me that I should avoid sand as a topdressing material!

[MorpheusPA]

I'm going to review the Micronutrient Application Guide and other guidance on the site. Can you please confirm the rates you recommend are at a per 1000sf application rate?

OK, that was a severe mistake on my part. Yes, those rates are per 1,000 square feet. Nice catch, thank you!

One thing I need clarification on is the ability to use iron. I understand the PH impacts this, but would this still be an issue for liquid iron sprays that absorb through the leaf?

There's no impact there, fortunately. If you spray, it will always work regardless of your pH.