# Soil Test & Low Potassium (K)



## ShaunD53 (May 19, 2020)

Finally got around to doing things right and getting a soil test before this season. I've come up with a plan to deal with the high Sodium by trying out some SuperCal Humic but don't know where to start when it comes to the low potassium. It seems that most fertilizer has a very limited amount of potassium in the mix so wondering what everyone out there does to correct a major deficiency in the soil. Also since this is really my first soil test feel free to let me know if I am missing anything else major to work on.


----------



## Deadlawn (Sep 8, 2020)

Some "lawn winterizer" fertilizers have K in them. Jonathan Green's version is 10-0-20:

https://www.google.com/search?q=winterizer+fertilizer&rlz=1C1AVNC_enUS561US561&oq=winterizer+fer&aqs=chrome.0.0j69i57j0l8.4553j0j15&sourceid=chrome&ie=UTF-8


----------



## ShaunD53 (May 19, 2020)

Wondering at this point in the season if an application of potassium sulfate 0-0-50 would be beneficial.


----------



## ScottW (Sep 16, 2019)

Welcome to TLF.
Please edit your location to something more useful. Unless you live inside Fort McHenry in Maryland, I have no idea where you are. Mid-atlantic soils are different from southeast soils are different from midwest soils etc. and you may get more specific and helpful info from other forumites who have more familiarity with your local soil type.

With high pH you can use ammonium sulfate as the bulk of your nitrogen source, and that will gradually bring the pH down over a period of year or more. Your pH is not so alarmingly high that you need to start adding elemental sulfur just to bring it down, but that's JMHO and others may chime in. It does mean that iron will be less available to the grass, so you may benefit from foliar sprays including iron. Lots of midwesterners deal with this.

For the low K levels you can apply sulfate of potash (SOP) or muriate of potash (MOP). Between those two, MOP is easier to find (often in blended fertilizers) and usually less expensive, but SOP would be preferred and you may need to call around to locate some (check with your local nurseries & landscape suppliers e.g. SiteOne). Both products will add K but MOP has a higher salt index and adds a bunch of Cl- ions to the soil. The grass itself won't be particularly sensitive to Cl but it can affect other aspects of soil chemistry. SOP doesn't have that effect and it also adds S which will be a benefit.
Don't freak out about this BTW. MOP is acceptable if that's all you can find, and the main thing is to get some K down, but SOP is preferable.

You can apply 1 lb of actual K per 1000 sqft on 1-month intervals. Start when the grass greens up and keep it up through the summer. If you get prolonged snow cover in the winter, stop applying K sometime early enough (September? I dunno, this doesn't really apply to my climate) to avoid promoting snow mold.
A good soil test will come with a recommendation of how much total K to apply based on your test results. From my recent reading on soil K (mine is also very low) it is pretty difficult to over-apply K to the point that you induce deficiencies elsewhere.

Mulch mow your grass clippings whenever possible to retain nutrients including K in the soil.


----------

