# applying sulfate of potash



## ktgrok (May 25, 2019)

My potash came today, and I want to spread it tonight or tomorrow. Just want to be sure - this doesn't burn the lawn, nothing to worry about as far as stress to the grass, etc, right? I put down Quicksilver today for broadleaf weeds (this morning) and am treating with various things for a current army worm invasion, and it is hot as hades out there, so the lawn is already somewhat stressed. This is supposed to help, and I do need it as soil test showed it was low, but I want to be sure I'm not going to hurt anything by putting it down along with everything else going on. What I have is Sulfate of Potash Magnesia 0-0-21.5. https://www.greenwaybiotech.com/products/sulfate-of-potash-magnesia?variant=1558062273&currency=USD&utm_campaign=gs-2018-12-12&utm_source=google&utm_medium=smart_campaign&gclid=CjwKCAjw36DpBRAYEiwAmVVDMHM98y8-mkvP6jLeyoxVF3vzzi5BL8kBF90zDVdLfIko8WPO3iEW5RoCHRcQAvD_BwE

My lab sample recommendations were to put down something like 6lbs per 1K of 0-0-50......but that's a ton to put down at once, so was going to put down that rate of this 0-0-21 stuff now, and then do another application later and see where I'm at. I've also been using some 15-0-15 lately, so it's getting some K already.


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## Ridgerunner (May 16, 2017)

Nearly all fertilizers are salts and can create plant stress. Although SOP has a lower Salt Index than most other fertilizers, it's still a salt. Really no way to predict if the increased stress would be the straw that breaks the Camel's back,
Are you applying K-mag due to low reported magnesium levels on your test?

Was this a Soil Savvy test?


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## g-man (Jun 15, 2017)

This is not the same product. This has magnesium. Does your soil needs magnesium?


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## Virginiagal (Apr 24, 2017)

When the lab says to apply 3 lb/k of a nutrient (which is what 6lb/k of 0-0-50 gives of potassium) they mean over the course of a whole year. In general you should not go over 1 lb/k of any nutrient in a single application. For this product, divide 21.5 into 100 to get the rate, 4.6 lb/k that will give you 1 lb/k of potassium. Stay at or under that rate. As with all fertilizers, water well after application. I don't know if the grass will be stressed with this in addition to all the herbicide applications you're doing. Maybe it would be good to wait awhile. For the 15-0-15, what rate did you use?


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## ktgrok (May 25, 2019)

Ok, so I double checked, and the label actually says to apply 10lbs per 1K, so I was well under that. And it is supposed to be a slower release, which should also minimize burning I'd think? The magnesium I'd read helps when applying Potassium as the potassium can block magnesium absorption or something?


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## Virginiagal (Apr 24, 2017)

The product is likely geared toward farmers, who don't like to make repeated applications. For lawns, better to stick with rule of the no more than 1 lb/k of a nutrient per application. Magnesium will tend to tighten up a soil, so if your soil is already high in magnesium, this would not be a good product to use. If your soil is low in magnesium, then it would be beneficial. Did your soil test mention magnesium?


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## Green (Dec 24, 2017)

@ktgrok, if you mean the 0-0-50, Sulfate of Potash, it does not burn compared to other things (like MOP 0-0-60 for example) and is relatively safe to be applied in heat. I applied it yesterday while it was 94F, and it's supposed to get close to 100 on the weekend. I wanted to get it down before the heat because Potassium helps with heat stress.


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## ktgrok (May 25, 2019)

Magnesium was at the low end of normal on the soil test. I'm not sure what you mean but tighten up? I have super sandy porous soil, so compaction isn't an issue.


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## Virginiagal (Apr 24, 2017)

Tighten up, meaning the particles stick closer together. If you have sandy soil, more tightness would be a good thing. Sounds like more magnesium would not be a problem for you. Here's some information on langbeinite:
https://www.cropnutrition.com/potassium-magnesium-sulfate-langbeinite
It says low salt index. It is mined, not manufactured, and dissolves slower than other potassium sources.

What is your CEC? If it's low, you might consider a spoon-feeding approach to fertilizing in general because low CEC soils don't hold onto nutrients as well. For example, instead of doing 1 lb/k of nitrogen per month during prime fertilizer season, you might do 1/2 lb/k every two weeks. Slow release products would be better too.


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## ktgrok (May 25, 2019)

I haven't had it checked but I'm sure my CEC is low. I am spoon feeding right now, about 1/3lb N every 10 days to 2 weeks. I had been wondering if there was any point to doing spoon feeding with organic, slower release stuff or if spoon feeding only made sense with fast release stuff.


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## Virginiagal (Apr 24, 2017)

Spoon feeding makes sense for fast release products. For slow release, it's not needed. You can use a higher rate, like 1.5 lb/k of a nutrient, per application for slow release too. I believe some products have a combination of fast release and slow release, so would be good to check.


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