Soil Test For Interpretation - May 2021

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levyd27
Posts: 6
Joined: May 22nd, 2017, 12:46 pm
Location: Southeastern Wisconsin
Grass Type: Northern Mix
Lawn Size: 5000-10000
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Soil Test For Interpretation - May 2021

Post by levyd27 » May 4th, 2021, 6:03 pm

Hi guys - I submitted a soil test for review back in 2017 and the recommendations were awesome. I've been putting in a ton of work over the past 4 years and my lawn now looks great. Lots of neighbor compliments :) Couldn't have done it without the recommendations from this forum, as well as the tons of valuable info all over the threads here! It's all very much appreciated!

My lawn is roughly 10,000 sq ft and I live in Southeastern Wisconsin.

I've included my 2017 test for comparison, along with the May 2021 test.

Over the past 4 years, my approach has basically been:
> Milorganite, mulch mowing and consistent watering as the staples.
> Secondary things added like: starter fertilizer (maybe 2-3 apps total in 4 years), gypsum, cracked corn, alfalfa pellets, boron, zinc, copper, aerify plus liquid aerator, azomite, and other things I'm probably forgetting.

So far this year, I've done:
> 1 app of milorganite
> 1 app of earth science sulfur (I'm guessing this wouldn't be typically recommended but couldn't help myself... I'm trying to lower the pH)
> 20 TBS each of boron, zinc and copper

At this point, I'm unsure of what my priorities should be. I was planning to do some more gypsum to get the Ca/Mg ratio to improve. I was also going to do another round of boron, zinc and copper. I'm unsure of how best to fertilize at this point, given how high my phosphorous levels are (I have no idea how they've gotten so high!). Any help is very much appreciated!

Thanks again guys!

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MorpheusPA
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Re: Soil Test For Interpretation - May 2021

Post by MorpheusPA » May 4th, 2021, 11:48 pm

You're in pretty good shape, actually. While I wouldn't've bothered with the sulfur (surface-applied sulfur ends up as 1/3 air pollution as sulfur dioxide, or smog, and about 2/3 going into the soil where it....well, didn't do what you wanted it to do because it's going to preferentially bind with the wrong things here...), what's done is done. I'm actually going to recommend a different sulfate below to shift one balance in favor of another.

How much sulfur did you apply? I'm guessing it as 10 or less than ten pounds per thousand square feet, resulting in less than 6 pounds of active sulfur per thousand square feet (which, at sulfur reaction rates [rather slow], I simply need to account for).

Twenty tablespoons each of boron, copper, and zinc? Per thousand square feet or over your 10K lawn (so 2 each per thousand square feet?) Duly noted, but stop. Discussion below.

Phosphorus levels are very high at this point, so no more needs to be added and you don't want any more.

Your current pH of 7.4 isn't that bad, really, and nothing grass will object to. It's being created by magnesium--vast amounts of magnesium--and you actually have a minor calcium shortage. The problem is that the sulfur is going to preferentially want to bind with the calcium. There's more of it, so it's more likely to encounter a calcium within the soil profile as it passes. There's more in soil solution. Magnesium is a little easier to dislodge, but...

So the sulfur you added is making a minor problem worse. This is why I frigging HATE pH results on tests. They give exactly the wrong answers to people without giving the more in-depth information required to give the proper care instructions to lower the pH the correct way (if it can be lowered at all, or if it needs to be lowered). Not to go off on a rant here, but I meet so many alleged "experts" who make recommendations without any understanding of soil chemistry who mindlessly recommend sulfur or aluminum sulfate (downright toxic if not monitored properly) and it bloody makes me sick. Grr. Sorry.

(Cough). Back to business. So let's do something a little freaky. We add calcium...but we don't want to raise your pH at all. In fact, we want to end up lowering it, or at least keeping it the same. Calcium sulfate (gypsum), very finely ground, will do that. It'll add calcium and, as the sulfate washes out, if it catches another calcium, it's all even. If it catches a magnesium or sodium...the pH actually goes down.

Just get the cheapest gypsum you can locate, and as much as you can swing on your budget, from your local landscape shop. Get the finest ground, but not a "fast" gypsum (which has some chemical bindings you don't really need). So a nice cheap gypsum. Up to 30 pounds per thousand square feet, if you can, but at least 10.

Don't expect much pH change, but the calcium levels should rise, magnesium drop a tiny bit, and sulfur levels rise a hair as well (the last will drop back to normal levels as sulfur washes out very easily as well--another issue the sulfur-recommending crew don't bother to mention).

Your potassium levels look great and this won't impact them too much.

In the minor elements, you're actually in good shape for the year. Copper is actually rather high--discontinue applications immediately! It's not dangerous by any stretch, but going past 4 PPM is certainly not necessary or recommended. Zinc is fine at 6 PPM. Manganese is very high at nearly 100 PPM (mine is higher and this is certainly not a huge issue), but it can start to interfere with iron at those levels. I compensated by sending my iron much higher, but yours is fine.

As for feeding, it's dealer's choice now. If you want to use an organic like soybean meal, great. I might avoid Milorganite due to the high phosphorus, but if you used it once a year and used something else with lower phosphorus at other times, I wouldn't object to that. The Milo was where the P levels came from, most likely. Most big box stores have other types of lawn feedings that are in the 5-7% nitrogen range with lower phosphorus, but they're a bit more pricey and don't contain the iron Milo does.

Since the iron isn't helping you all that much, it's not critical for your lawn.

If you prefer a synthetic feeding, go with something that has a high nitrogen level and low everything else--so a high first number and low second and third. You seem set on organics, which is great.

Feed on the normal schedule--so, for organics, Mid-May, September, October, and then a synthetic at the last cut with high-nitrogen to winterize.

Recommendations:

May: Apply up to 30 pounds per thousand square feet of gypsum.

September: Apply up to 30 pounds per thousand square feet of gypsum.

levyd27
Posts: 6
Joined: May 22nd, 2017, 12:46 pm
Location: Southeastern Wisconsin
Grass Type: Northern Mix
Lawn Size: 5000-10000
Level: Experienced

Re: Soil Test For Interpretation - May 2021

Post by levyd27 » May 5th, 2021, 7:56 am

This is super helpful. Thanks so much for the detailed response. I really appreciate you taking the time!

To answer your questions (and ask a few more of my own, if you don't mind):

> I used 50lbs total of earth science sulfur (so 5lb per thousand sq ft). Per your smog comment, I'm guessing this is why my throat has been sore for the past 2 days (forgot to wear a mask)!
> Sorry, I should have elaborated on the 20 TBS :) It was 20 TBS each, in total... so 2 TBS each per thousand sq ft.
> Do you see any issues with me continuing to use the aerify plus that I spray that helps to aerate/condition the soil, while also adding OM at the same time?
> As for copper, I was trying to increase it because my understanding was that this could help with disease suppression and that it's ideal to get it closer to 10-15 ppm? I have trouble in the late summer with rust and I think some other diseases too. Figured it's easier long term to raise the copper and stop it at the source, rather than to keep spraying fungicides.
> For boron, I was adding that because I understood that getting it to about 1.2 ppm was ideal?
> For zinc, I understood that getting it to at least 6 was the goal, with 10 ppm being ideal...

...I guess I was getting faulty information about these 3 micros?

Makes sense on the gypsum, will do!

As for feeding, that makes sense. I'm curious... if it were you, would you go with high nitrogen synthetics or just do regular apps of organics like soybean? I'm open to either, but just curious if you think one is better than the other.

And just one last question -- for phosphorous, potassium, and the micros... are these the types of things that will drop over time after I stop adding them, and that I should monitor each year through soil testing? Or should I just assume that I'm now forever good on these, make sure I don't increase them, and just move into a more simple approach of just gypsum and normal feedings each year going forward?

Thanks again!

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MorpheusPA
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Re: Soil Test For Interpretation - May 2021

Post by MorpheusPA » May 5th, 2021, 10:15 am

The smog will be a very slow generation process, so no, you probably didn't notice it. My throat has also been a mess, which I attribute to the allergens present. I'm seriously considering a Zyrtec. It's more of a "whole atmosphere" consideration and a "no reason to pollute if you don't have to." 5 lbs per thousand isn't something I really need to account for all that much, so we can simply ignore it. It'll work out to a grand total of 3 pounds of sulfur actually making it into the soil.

You can continue to use the Aerify as much as you want! Or, if you'd rather, check out the Soil Conditioner/Kelp Help formulas on this site. Same idea, same effect, a tenth the price. Chemistry cooked up by Andy and yours truly. I've modified it a bit over the years to make it even cheaper and easier to use by working with SLS powder instead, so you might want to look at the threads about it, or just ask after you've looked at the Soil Conditioner under the FAQs.

Copper's great for disease suppression, but generally as a spray when the disease rears its head. At that point, a spray of copper sulfate will kill most fungal diseases because they can't stand the pH shift or the copper itself. And it doesn't take much, just a thin spray in water. So in this case, a minor bit of copper exposure will kill a fungus (or, why copper banding on a roof will keep a roof moss-free as well--just the tiny bit of copper runoff is fatal to it).

Copper in the soil forms part of the natural disease suppression in the plant. In that case, however, you only need a few PPM as the plant doesn't need much copper overall. It's not a major element. So they're really two different things.

Zinc will vary and testers have differing standards. Mine is about 3-5 as the floor. At 6, you have no problems. But zinc is an oddball in that if it were 100 you'd still have no problems.

Boron is rather touchy, although grasses aren't particularly boron-sensitive in either direction. If you were to target 1.2 PPM, that would be fine. I'd consider it a bit high for most purposes, but any plant you'd grow wouldn't have a problem with it. Problems start around 2 PPM for boron-sensitive plants. You'll often see boron damage on your vegetables first. Grasses won't show symptoms of boron shortage or boron excess until it gets really ridiculous, and while my normal target is 0.7, 0.62 is more than close enough for this year.

How fast things drift is...complicated. It depends on your soil's EC, the local rainfall, and how the soil is treated. Including what you grow. So your grass (and my grass) function differently than my gardens. I think I get more rain than you do, overall, but I don't irrigate, so overall...who knows? Our EC values are actually extremely comparable.

With your soil, I'd say you'd be safe testing every 3-4 years as an Interested Hobbyist. If you want to go to crazytown like the rest of us, yearly is certainly not a problem.

Nitrogen drifts fast as it gets used up and washed out easily. Phosphorus is extremely stable and doesn't wash out easily. Potassium does wash out--but not quickly. Copper is more like phosphorus. Calcium bonds pretty tightly, while magnesium's bond is a little looser (but tighter than potassium's). And adding things can push out other things, depending on what they are, or they can cause chemical reactions that will pull things out of the soil and get rid of them.

But the roots of the plant are also always mining resources from lower down, drawing them up into higher roots and leaves, and then depositing them at the surface as the leaf (and root bits) die and decay. So things that you'd think are gone make a second appearance...

levyd27
Posts: 6
Joined: May 22nd, 2017, 12:46 pm
Location: Southeastern Wisconsin
Grass Type: Northern Mix
Lawn Size: 5000-10000
Level: Experienced

Re: Soil Test For Interpretation - May 2021

Post by levyd27 » May 5th, 2021, 12:25 pm

Perfect, this is exactly what I was looking for!

Really glad I posted because I think you just saved me from myself :)

Have a great summer and thanks again!!


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MorpheusPA
Posts: 17162
Joined: March 5th, 2009, 7:32 pm
Location: Zone 6 (Eastern PA)
Grass Type: Elite KBG
Lawn Size: 10000-20000
Level: Advanced

Re: Soil Test For Interpretation - May 2021

Post by MorpheusPA » May 5th, 2021, 3:27 pm

Thanks, you too! And check out the Soil Conditioner/Kelp Help pages on the FAQs. They'll save you a fortune compared to commercial aeration chemistry.

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