# Late season potassium application opinions



## BenC (Mar 27, 2018)

I'd be interested in hearing folks opinions on potassium loading turf prior to dormancy. It's a very important application in other perennial crops, not sure about turf. In other crops it helps withstand winter injury and stores well for the transition out of dormancy but doesn't delay dormancy in fall. I just put some down some with that in mind, with a smigeon of nitrogen to aid uptake. Anybody doing this? Thoughts? Unecessary in turf?


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## Colonel K0rn (Jul 4, 2017)

For what it's worth, I had a 50# bag of 28-0-3 that I put down the day before I came over. This put my total K2O input that I've tracked to 2.2 #/M so far this season. I've been pretty light on my applications, but I need to get another soil test done to see what kind of improvement I've made this season, and whether or not it would warrant including more K into my application schedule.


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## Ware (Jan 28, 2017)

Fall applications of Potassium are often recommended for spring dead spot management. I had SDS this year and my soil test revealed a K deficiency. That said, NC State says fall K had no effect on SDS in their research.

Read more at: https://www.turffiles.ncsu.edu/diseases-in-turf/spring-dead-spot-in-turf/


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## Colonel K0rn (Jul 4, 2017)

One other thought that @thegrassfactor brought up in his show this evening was K loading to help Zoysia help to harden off against rhizoctonia and rust during the transition period from Summer-Fall.


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## BenC (Mar 27, 2018)

I didn't feel like digging for the reference, so I just reached out to the UGA turf specialist for confirmation. Paraphrasing: turf grasses are able to consume potassium at luxury levels (i.e. take up and store more potassium than what they need at the time). Benefits include physiological, pathological, and stress abatement as well as helping with winter injury, and spring green-up. He likes 1lb/1000 in the fall.
Basically turf responds like other perennial crops I have more experience in. In the southeast we're deficient with K lots of times, so loading up the soil helps too. Other soil types I've worked on fix K, so getting soil levels up took longer on those specific calcareous soils.


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## BenC (Mar 27, 2018)

I guess I should've put this in the fertility section. oops


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## Ware (Jan 28, 2017)

BenC said:


> I guess I should've put this in the fertility section. oops


Moved. :thumbup:


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## g-man (Jun 15, 2017)

There is risk in cool season lawns with late potassium.

https://mobile.twitter.com/djsoldat/status/833701627739664384

Also, the latest research from Doug Soldat also shows that the sand(top dressing) could be a source of potassium to the lawn. https://thelawnforum.com/viewtopic.php?t=753&start=80


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## Suburban Jungle Life (Mar 1, 2018)

+1 I prefer to put my K in mid to late spring to help with summer. I also put some down early fall so new seedlings have some readily available but that's it. I don't want to increase risk of snow mold. If you don't have snow sitting on the ground, you live in TN or something like that, maybe this isn't a problem for you then.


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## BenC (Mar 27, 2018)

@g-man that's an overload of an element can be consumed at luxury levels, it would definitely throw a plant out of balance. A symptom that is common to some pathogens (fungus, nematodes) sometimes is a low plant tissue potassium percentage. That helps to explain why the mold issue might be worse on turf that is "out of balance" by being overloaded with potassium. 1#/1000 of potassium at a single application is less efficient than their application approach, and I'd bet they put way more pounds to it than the UGA recommendation that I'm talking about. All just food for thought.
I don't know anything about cool season grasses, but the effects I'm talking about are all physiological and timing counts. I can't imagine any need for large or very regular applications of K in season on a cool or warm season grasses.


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## BenC (Mar 27, 2018)

Tried to get to that link, but having trouble getting it to play. are they talking about green sand? that sounds interesting.


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## BenC (Mar 27, 2018)

Nice link @g-man, just finishing it now. I don't deal with snow mold, but looks like any potassium makes turf more susceptible to the mold. The sand/potassium link with feldspar based sands makes lots of sense, we just have blow sand/ beach sand without any k in it. For winter hardiness and potassium, on some turf species without snow mold issues, it appears from his work shows that potassium helps winter hardiness. For guys with poa problems, put less or no potassium at fall time, to induce winter injury to poa. 
This whole issue is not super straight forward in turf! Looks like I'll need to summarize get this information in order to make sense out of it.


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## g-man (Jun 15, 2017)

Yes putting green sand. This link came from OSUturfman.

Around minute 52:38, he asked folks from different golf courses in the US to send him samples from the sand they used. He then analyzed the sand K %. It range from 0.10 to 2.20%. It is really interesting stuff.

This was just a TurfNet presentation of what he is working on and some early observations. Bill Kreuser is also doing some really cool research on P (we dont need as much as we think). I know it is cool season research, but some of it could apply to the warm season.

https://mobile.twitter.com/UNLturf/status/999656608316747777


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## Ridgerunner (May 16, 2017)

@BenC It appears you guys have pretty thoroughly covered most of the possible concerns and advantages regarding potassium applications. I'm not aware of any studies regarding adverse results due to K applications to warm season turf and the only studies I'm familiar with regarding adverse reactions on cool season turf are limited to the studies g-man cited (limited to snow mold on bent and Poa A.). In my early days of "More is Better", I used to apply [email protected]/M of triple NPK to my KBG with no problems with snow mold or any other observable issues, but my experiences ahouldn't be considered conclusive.
Anyway, the one concern that does come to mind, especially with sandy, low CEC soils with low Mg values would be a possible Mg deficiency that may occur when K:Mg ratios are greater than 1.2 to 1. Just something for you to consider.


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## Delmarva Keith (May 12, 2018)

Well @BenC you asked for opinions so here's one  .

I generally fert with 2-0-1 ratio as that represents the ratio of N to K in healthy grass tissue. I add P as soil testing indicates. Never had an issue with snow mold. Grass needs K and even adequate K soil can leach the K away. K is not an environmental concern. Give it regular K. :thumbup:


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## Green (Dec 24, 2017)

BenC said:


> The sand/potassium link with feldspar based sands makes lots of sense, we just have blow sand/ beach sand without any k in it.


Isn't Felspar pink?

The latest greens grade SOP I bought looks like pink sand. Hmmmm...


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## Green (Dec 24, 2017)

Delmarva Keith said:


> Grass needs K and even adequate K soil can leach the K away. K is not an environmental concern. Give it regular K. :thumbup:


That's probably why most off shelf fertilizer has K in it. More like an 8:1 N:K ratio typically, but still beneficial no doubt.


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## Green (Dec 24, 2017)

BenC said:


> In the southeast we're deficient with K lots of times, so loading up the soil helps too.


Same in the Northeast. Plus, the sandy soil tends to leach it over time.


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## RDZed (Jul 13, 2018)

Here's an interesting read about winter K apps. I might load now being I gave clay soil and level land...

https://extension.psu.edu/can-i-apply-potash-in-winter


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