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Potassium App

J Ross

LawnSite Member
Location
Michigan
Hello all,

Recently had a soil test done and it indicated the lawn had 20.24 PPM of Potassium with an Optimal range of 38-72 PPM. When I try to convert PPM needed to Lbs/1000 I keep coming up with 8 Lbs and change which seems really high. I may be complicating this and would love some advise.
All other macro nutrient concentrations were fine but my calcium PPM was 390.25 which seems a touch high. I add this information in case the two nutrients are interrelated in some way.

Thank you all for your time.

-JRoss
 

RigglePLC

LawnSite Fanatic
Location
Grand Rapids MI
Normally parts per million times two equals pounds per acre.
But there are a few exceptions and complications.
https://edis.ifas.ufl.edu/hs1229

Lesco 24-0-11 would be good.
Commonly potassium is low on sandy soils with low organic matter because potassium is mostly water soluble. After several good rains or irrigation it can be washed out--leached away.
Most experts recommend that a small amount of potassium be applied several times per year--with each application, usually.
If you can increase soil organic matter--this will help hold the potassium as a cation with a positive charge, it likes to stick to organic matter with a negative charge.

Maybe the soil science majors on our site can add more helpful information.
Are you on sandy soil? You need to know the optimum range and best type of fertilizer for the job.

https://extension.psu.edu/turfgrass... used in protein, sugar, and starch synthesis.
 
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OP
J

J Ross

LawnSite Member
Location
Michigan
Riggle,

Thank you for the quick and detailed response. I am dealing with sandy soil. This particular lawn has been getting the old Milorganite at bag rate every 30 days or so and Scott's starter every spring the last 2 years.
I am just starting to learn about fertilizer and micro applications so I apologize for my ignorance in advance. With a 24-0-11 I would want to wait until average temps are back below 85 correct? Also I am surprised at the 11% K recommendation. I would assume for maintenance applications 11% would be ideal. However, with as low as this yard is do you think it will be enough? I suppose my previous question also begs the question is potassium something you want to bring up gradually or all at once?

Again, thank you so much for your time and for educating me.

-JRoss
 

RigglePLC

LawnSite Fanatic
Location
Grand Rapids MI
We are typing at the same time--LOL!
Good to hear from a Michigander.

No need to wait until temps come down to 85 to apply the 24-0-11--provided you apply at the correct rate and get an even spread.

I am learning about potassium at the same time using Bing.com.
Sandy soil is a problem as it loses potassium easily.
And--of course--Milorganite has no potassium at all.
Years ago, I used to base my potassium ratio using Scotts Turfbuilder formula, at the time, 28-4-4. To me that meant use potassium at each application at 1/7 as much as the nitrogen.

http://ipni.net/publication/bettercrops.nsf/0/CBEDB7ABC709126185257D31005E9FF7/$FILE/ BC-1994-3 p6.pdf
 

RigglePLC

LawnSite Fanatic
Location
Grand Rapids MI
Actually the calcium at my house is 850 parts per million, 71 percent of my base ratio, or at least it was, 20 years ago, when I had my last soil test. This is OK.

Potassium cannot be corrected all at once. That would burn the grass. A gradual increase is better. And because of the rapid loss from sandy soil--it should be included in all, or at least most, of your fertilizer applications.

The problem is partly due to the low CEC (cation exchange capacity) of sandy soil. As a cation (positive charge) potassium is not held tightly and quickly leaches out. Apply potassium frequently and a little at a time.
 
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grassmasterswilson

LawnSite Fanatic
Location
nc
Add more potassium throughout your program. 1:1 if you could. May consider a sulphate if potash app. Potassium is soluble so I usually see it fluctuate.
 

HighChiefKC

LawnSite Member
I’m in sand also. We use a 24-0-5, 4 out of 5 rounds, and every once in awhile I come across soil results that’s low in P. Our supplier has a 0-0-60 I believe, that last number May have been 40, but I’m pretty sure it was 60. I’ve used it on a couple of lawns this year with no harm done. If the K and P are low, we have a 6-24-24 or something like that. Hard to remember all these numbers.
I have a customer that is an old school Chemlawn former employee. He has me put down 15-24-10 down once a month all season long.
 

Yatt

LawnSite Senior Member
Location
Onalaska, WI
Hmm.. my apple trees are lacking on thing and that is potassium. Apples take a lot out of the ground. I am going to side dress the rows once the go dormant.

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RigglePLC

LawnSite Fanatic
Location
Grand Rapids MI
Wow, amazing apples. Are they Honey-crisp?
I hope you wife plans on making lots and lots of applesauce.

Soil tests are good. I think it may be time for a tissue test. Costs more and it is better.

 
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