# Potassium Deficiency



## upNorth (Oct 7, 2020)

I just received my end of season soil analysis and it showed a severe potassium deficiency (4.93 ppm) with a target of 38-72.

I was going to use sulfate of potash at a rate of 1.8 lbs of potassium per 1,000 square foot twice next summer and see where I am at the end of the season.

Should I do more to correct?


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## g-man (Jun 15, 2017)

@upNorth I moved this to the soil folder.

That range is the same one that MySoil gives. Their test methods and ranges are not proven ones. I suggest you use a real lab. The first post in the Soil Folder will give you some guidance on selecting a good lab.


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

upNorth said:


> I just received my end of season soil analysis and it showed a severe potassium deficiency (4.93 ppm) with a target of 38-72.
> 
> I was going to use sulfate of potash at a rate of 1.8 lbs of potassium per 1,000 square foot twice next summer and see where I am at the end of the season.
> 
> Should I do more to correct?





g-man said:


> That range is the same one that MySoil gives. Their test methods and ranges are not proven ones. I suggest you use a real lab. The first post in the Soil Folder will give you some guidance on selecting a good lab.


I concur with g-man's recommendation to make sure you have soil test results from a good lab before basing fertilizer choices on the lab test results.

For a potassium deficiency, I also agree with your choice of using sulfate of potash (0-0-50) to remedy it. SOP is preferable for lawns over muriate of potash (0-0-60 to 0-0-62, aka potassium chloride) as SOP has a lower salt index.

I would suggest applying potassium at a rate of no more than 1#K / ksqft per month. So, instead of applying twice at 1.8 lbs of potassium per ksqft, I'd suggest making monthly applications, of only 1#K / ksqft.

In an area which sees extended snow cover in the winter, high potassium levels increase the risk of snow mold, so I would also recommend making no large applications of potassium after Labor Day. (I'm presuming that persistent snow cover of 45+ days in the winter is highly likely in North Dakota.)

For me, personally, in New Hampshire, which has first and last frost dates very similar to Fargo, ND, for a seriously potassium-deficient lawn, I'd suggest making applications of sulfate of potash (0-0-50) at a rate of 2# product / ksqft (i.e 1#K / ksqft) about a month apart, starting when the ground is completely thawed (probably around April 20) and repeated monthly until around August 20. That's what I do for our lawn which is perennially deficient in potassium due to a combination of sandy soil and relatively high annual rainfall compared to many portions of the USA. If, after a repeat soil test, you find that your soil is holding onto your potassium, you can back off from monthly applications to less of them each year. In the span of the last 6 years, I've backed off from monthly potassium applications (5-6 each year) to only three applications at 2-month intervals. (Around April 20, June 20, and August 20 for me.)


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