# Potassium



## Schiavo (Aug 18, 2020)

Soil test says low K. Soil here is generally sandy and I hear that can leach K quickly. What are some options for getting this to optimum levels?

My soil test:


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## massgrass (Aug 17, 2017)

I'm in a similar situation and do a couple of potassium sulphate/sulphate of potash (SOP) applications earlier in the season.


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## Jacks_Designs (May 4, 2020)

Schiavo said:


> Soil test says low K. Soil here is generally sandy and I hear that can leach K quickly. What are some options for getting this to optimum levels?
> 
> My soil test:


I'd wait until spring when grass is growing to apply potassium.


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## Green (Dec 24, 2017)

Jacks_Designs said:


> I'd wait until spring when grass is growing to apply potassium.


Agreed. Now is not a great time for Potassium in the Northeast. If you apply now, it is easier to leach over Winter, and may worsen snow mold. I personally don't like to apply anything later than necessary for these reasons.

April or May is a great time to start applying Potassium.


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## jskierko (Sep 5, 2020)

Ditto what everyone else has said. Wait until spring for K. I'd apply SOP (0-0-50) at 2lbs/k sq ft on a monthly basis starting in the spring. SOP can be hard to source locally, so I'd ask your local peers if they know a supplier. I have a 50lb bag that I just got from Kelp4Less and that was about the cheapest that I could find online. Other sites may appear to be cheaper but they will charge you more for shipping than for the product whereas K4L ships for free (it still is $$ on a per app basis though for a yard of your size).


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## g-man (Jun 15, 2017)

@Schiavo I moved this to the soil folder.

Your soil is not low in potassium. Using MLSN, low would be below 37ppm in the mehlich 3 test. Next year do apply potassium to account for leaching and what the turf uses with a long term target around 150ppm.

You also don't need more phosphorus. It is at a high level.


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## lawnphix (Apr 13, 2019)

My turf is also deficient and am waiting til spring (MA. Zone 6b). I'll also spoon feed some liquid in the summer to aid with the summer stress. Got some 0-0-50 granular at Kelp4Less for about $1.10/lb. with a 15% off coupon (lawnphix). The powder is more expensive but a true SOP.


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## Methodical (May 3, 2018)

OP, if you have a Site One in your area check with them. The Site One in my area has the 0-0-50 SOP 50lb bag.


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## Grassmasterwilson (Jun 11, 2018)

What is your preference in potassium source? SOP seems to be the best with many suggesting to stay away from MOP

But if you are trying to correct a Large deficiency throughout the year is source That important?


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## Schiavo (Aug 18, 2020)

g-man said:


> Your soil is not low in potassium. Using MLSN, low would be below 37ppm in the mehlich 3 test.


G-man I'm going to need your help unpacking this.


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## Schiavo (Aug 18, 2020)

Methodical said:


> OP, if you have a Site One in your area check with them. The Site One in my area has the 0-0-50 SOP 50lb bag.


Thanks Methodical, Nashua has it in stock. I think I'll plan for next spring though, as recommended.


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## Deadlawn (Sep 8, 2020)

g-man said:


> @Schiavo I moved this to the soil folder.
> 
> Your soil is not low in potassium. Using MLSN, low would be below 37ppm in the mehlich 3 test. Next year do apply potassium to account for leaching and what the turf uses with a long term target around 150ppm.
> 
> You also don't need more phosphorus. It is at a high level.


Interesting how different soil test labs categorize "optimum range". The UMass lab I use shows very different optimum ranges. If using these ranges, the OP would have no deficiencies and his P would actually be off the charts.

That being said, Umass uses Modified Morgan measured extractable in ppm, so this may be a case of comparing apples to oranges.


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## g-man (Jun 15, 2017)

Yes, apples to oranges.


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## Deadlawn (Sep 8, 2020)

g-man said:


> Yes, apples to oranges.


I decided to Google "mehlich 3 vs modified morgan" and came up with some interesting stuff on how different these results can be. It does appear the optimum ranges are adjusted to compensate..........at least somewhat. Is this too much to assume?


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## bernstem (Jan 16, 2018)

@Deadlawn Optimum ranges given by the lab are adjusted for the testing method used. There can be further variability in optimum ranges depending on philosophy of interpretation and soil type, but breaking that down can be a very deep rabbit hole. Bottom line is you should generally follow the lab guidelines (assuming you use a reputable lab) unless you want to go down that potentially very deep rabbit hole.


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## Ridgerunner (May 16, 2017)

bernstem said:


> @Deadlawn Optimum ranges given by the lab are adjusted for the testing method used. There can be further variability in optimum ranges depending on philosophy of interpretation and soil type, but breaking that down can be a very deep rabbit hole. Bottom line is you should generally follow the lab guidelines (assuming you use a reputable lab) unless you want to go down that potentially very deep rabbit hole.


Well said. :thumbup:


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## ken-n-nancy (Jul 25, 2017)

Schiavo said:


> Soil test says low K. Soil here is generally sandy and I hear that can leach K quickly. What are some options for getting this to optimum levels?
> 
> My soil test:


I concur with the recommendations you've received above to postpone applying potassium to the spring, and to ensure that you apply Sulfate of Potash (0-0-50), rather than Muriate of Potash (0-0-60) as the latter is harsh on the grass in comparison to Sulfate of Potash.



Schiavo said:


> Thanks Methodical, Nashua has it in stock. I think I'll plan for next spring though, as recommended.


When you say that "Nashua has it in stock" do you mean Nashua Farmer's Exchange? Mind sharing their price for it?

I've been getting my sulfate of potash (0-0-50) in 50-pound bags at Milford Agway. I don't recall the price off the top of my head, but I'm always looking for better deals on lawn fertilizers.


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## VALawnNoob (Jun 9, 2020)

i got my 0-0-50 at SiteOne for roughly $40 for 50# bag


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