AGN015 2020 Soil Test

Learn how improving your soil can lead to a better looking lawn
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agn015
Posts: 150
Joined: April 2nd, 2016, 11:32 am
Location: Long Island, NY (Suffolk County)
Grass Type: Hogan Blend - GTO/Hemi/Hot Rod TTTF Everest/Award/Everglade/Midnight KBG
Lawn Size: 10000-20000
Level: Experienced

AGN015 2020 Soil Test

Post by agn015 » April 1st, 2020, 10:07 am

Good morning everyone,

I just got my 2020 soil test results back. This is now my 5th year of soil tests and I'm pretty happy with how the numbers are looking. I'm not sure why the pH increased so much as I've never put down any lime, ever. Does an increase in potassium drive an increase in pH? I was able to get 6 SOP apps down from April through September. I mulch mow always, including all of the leaves I can get my hands on. Maybe in another 5 years, I'll move up to an acceptable OM number.

Last year I kept up with serenade apps starting mid-May through October 21. I was battling powdery mildew in the spring which then turned into another disease I couldn't ID? I had a small section of grass in full sun get hit pretty hard with disease/drought stress and die off mid-summer. Those spots recovered well during the fall nitrogen regimen and you'd never know they died off looking at them now.

However, during the fall regimen I did notice a disease that resembles started as rust, then maybe turned into leaf spot or melting out. In late fall, the lawn thinned out because of this. Die out was most noticeable in the shady areas. The shady areas still show signs of this yellowing, but it seems to be growing out. I have refrained from using any chemical fungicide in hopes that the good guys will win the war. I've only introduced serenade and I'm wondering if this is the year I should add companion to the mix. I'm planning to continue mulch mowing, but may bag once or twice if I notice disease again.

I do have some areas of undesirable turfgrass. I'm not sure if this is the year I try to glyphosate them. The fall preM definitely knocked out a good portion (maybe even 100%) of poa annua as I haven't seen any yet this year.

Other than the disease pressure, the grass is generally weed free and the sunnier areas are coming out of winter in great shape. I have been pretty happy with the color, but after seeing the pH I wonder if it could be a darker green...

Micros are definitely on the table again this year.

Thanks to all help on this forum for getting me to where I am!

2019 test results thread: viewtopic.php?f=11&t=24783

2020 test results: Image

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andy10917
Posts: 29133
Joined: February 23rd, 2009, 10:48 pm
Location: NY (Lower Hudson Valley)
Grass Type: Emblem KBG (Front); Blueberry KBG Monostand (Back)
Lawn Size: 1 acre-2 acre
Level: Advanced

Re: AGN015 2020 Soil Test

Post by andy10917 » April 1st, 2020, 8:21 pm

AGN:

Alright, let's get to your questions first:
I'm not sure why the pH increased so much as I've never put down any lime, ever. Does an increase in potassium drive an increase in pH?
Oh, I could go on for hours, but you'd probably go glassy-eyed with the chemistry. Pound per pound, Magnesium (atomic number 12, +2 valence) is 1.7X the pH effect of Calcium (atomic number 20, valence +2) and that is roughly twice the pH effect of Potassium (atomic number 39, +1 valence). So, Potassium is unlikely the "villian". What I see is a jump in Magnesium, which is the strongest pH effect. Whether that was added accidentally or just from sampling differently I don't know, but that's the primary "villian".
Maybe in another 5 years, I'll move up to an acceptable OM number.
You got a 0.4% increase in OM - that's nothing to sneeze at in a year. As we always say, this is a marathon. The people who think they'll get an OM% jump from a couple of bags of Milorganite and mulch-mowing are delusional. I've known exactly one person in my many years of doing this that could deliver a 1% jump year after year, but he was insane in his dedication to the task.

So - let's look at your results:

A 7.42 TEC is not a huge issue - it's a touch sandier than a Loam (which starts at a TEC of 8), but staying on the OM% will get you there. Really - stay on the OM supplementation.

In the cations, we hit the target for your current TEC with Potassium - but that's a moving target as the OM rises. A couple of applications at 2 lbs/K will keep it in line with the rising TEC on OM additions. Like two application at 2 lbs/K over the course of the season. I aimed the Potassium number for 4% Base Saturation, and you hit 4.04% - nice!

Phosphorus is good.

Iron is OK but mostly unavailable. Consider making some of the Nitrogen from Milorganite, which will supply chelated Iron for color.

In the micro's, only Boron is in need of work. You've got that covered, right?

agn015
Posts: 150
Joined: April 2nd, 2016, 11:32 am
Location: Long Island, NY (Suffolk County)
Grass Type: Hogan Blend - GTO/Hemi/Hot Rod TTTF Everest/Award/Everglade/Midnight KBG
Lawn Size: 10000-20000
Level: Experienced

Re: AGN015 2020 Soil Test

Post by agn015 » April 1st, 2020, 10:23 pm

Thank you Andy!

Hmmm I wonder where the magnesium is coming from? Maybe it was a sampling error but I’m not sure. Both last year and this year I used a proplugger to grab the inch between 3-4” depth.

Would adding OM unlock some magnesium that was previously unavailable in my soil? My first soil test 5 years ago had you asking me if the “lawn was treated heavily with dolomitic lime? For a long time?” Maybe some of the magnesium from that is becoming available?

Don’t get me wrong I’m very happy with the 0.4% jump in OM! I actually have a few bags of leaves hiding in my shed that are due to make it out to the lawn soon. No leaf leaves my property and I try to gather up as many as I can from my block.

Of course a couple weeks ago I bought 150lb of SOP and now I only need 50lb. That’s fine I can either save the surplus for next year or use it on my moms lawn.

Wow I can’t believe I hit the potassium goal spot on!

Since I only need to put down 2 apps at 2lb/k would you have any suggestions for timing? Should I drop 1 app now and another after summer? Or is it better to drop it the same time as I drop some nitrogen?

With my TEC would it make sense to split it into 4 separate 1lb/k apps throughout the season? I wouldn’t mind the extra application effort if it makes a difference. Or at
I overthinking it? I’m actually a little disappointed I hit my potassium goal so soon. I was really looking forward to dropping monthly apps of SOP.

I have plenty of bay state left from a haul last year so I’ll absolutely use that for some nitrogen this year.

I’m good with boron as long as it’s still 3tbsp/k every 60 days. With potassium taken care of I’ll put more focus on boron.

You’re the best, thanks again!

agn015
Posts: 150
Joined: April 2nd, 2016, 11:32 am
Location: Long Island, NY (Suffolk County)
Grass Type: Hogan Blend - GTO/Hemi/Hot Rod TTTF Everest/Award/Everglade/Midnight KBG
Lawn Size: 10000-20000
Level: Experienced

Re: AGN015 2020 Soil Test

Post by agn015 » April 10th, 2020, 12:17 pm

Grass is still waking up. Sunnier spots are looking fantastic while the shady spots are still lagging behind. My plan is to drop the first 1lb of K around the same time I drop Bay State and boron. I also lied about poa annua, there's def plenty of that still hanging around...

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