# Chlorides in 0-0-60 Muriate of Potash



## OKC Lush (May 20, 2020)

Time and time again I hear that it is preferable to use 0-0-50 Sulfate of Potash instead of 0-0-60 Muriate of Potash because the latter is harsh on the soil due to chlorides. I plan to spread 6 lbs of potash to my Bermuda over the next couple of years, with multiple applications of 1 lb potash per 1,000.

I'm hoping to find some more information that help people like me who are struggling to decide between 0-0-50 and 0-0-60 to raise Potassium levels. I have no idea how to quantify the effects of chlorides at these quantities and the time period of which they might reside in the soil.

The cheaper option is 0-0-60 Muriate of Potash, which is Potassium chloride (KCl). What actually happens to the KCl molecule once it enters the soil? Do the chlorides eventually leach away or do they continue building up over time?

Yes I know that I am overthinking this, but that's half the fun.

Thanks!


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## Ridgerunner (May 16, 2017)

Although plants do use chloride, the amount is so small that (like Nickel) it is not listed as a monitored nutrient, not even as a micro-nutrient. The amount used by the plant is easily supplied through natural rainfall. Sulfate, on the other hand, is used in amounts that are only exceeded in importance by NP and K and there is no known toxic level. Depending on the method used to measure it, recommended sulfate levels fall between 15 and 60 ppm. Necessary chloride levels are so low, that I've never seen it quantified (but I haven't looked that hard).
Chloride is an anion, so much of it can leach below the root zone, however, as an anion it can also combine with cations, particularly with Ca.
Nearly all fertilizers are salts and chloride salts are particularly high on the salt index. Salts are not good as they create conditions that interfere with water movement and uptake by plants. The most common method for monitoring soil salt levels is by testing for soluble salts (EC- electrical conductivity test- Some labs include it in their "complete" soil analysis tests) and avoiding detrimental levels above 2.0 dS/m depending on the turf type.
Chloride accumulation in plants can become toxic.
Recommended max levels for chloride is 100 ppm with 350+ being considered deadly for most plants. If your EC (soluble salts) are high, then you might want to test for chloride to see if that's the likely source. Labs can test for chloride for a charge of around $10.
For almost all lawns, using potassium chloride is not likely to become a problem, but then where is you plant getting it's Sulfate?


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## HoosierLawnGnome (Sep 28, 2017)

The issue with chlorides is they are much harsher on a soil's microbiology. They kill it more easily.

So, its not like it builds up per se.

That decreased biological action inhibits the ability to break down material in the lawn, which helps acidify it.

So, if you have a high pH soil, thats why its better to use something gentler like SOP.


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## uts (Jul 8, 2019)

How big is the difference for the SOP vs MOP? Even for a lawn your size 1 50lb bag provides you 1lb of K so spread out over the year the cost does not seem that huge.. I think ..


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## OKC Lush (May 20, 2020)

For 50 lb bags, my cost is $23 for MOP and $44 for SOP. I'm still making the rounds to try and find cheaper SOP. The price delta is even smaller when taking sulfur into account.

Ridgerunner is like an encyclopedia -- so helpful.


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## HoosierLawnGnome (Sep 28, 2017)

I use MOP 0-0-60, but my price difference is substantial. Those sound like good prices to me for bagged product.

SOP is 4X more than what I can buy bulk MOP for, so it's a nonstarter for me. If I apply it 100 lbs per app, 4-5X per year, it saves me hundreds of dollars.

When i managed 7k sf, $20 was a non issue.

ETA: I have been applying about 300 lbs of MOP per year for the last several years, which is a slower pace, so as not to push pH. I'm taking the long game approach to correcting the K.


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## uts (Jul 8, 2019)

OKC Lush said:


> For 50 lb bags, my cost is $23 for MOP and $44 for SOP. I'm still making the rounds to try and find cheaper SOP. The price delta is even smaller when taking sulfur into account.
> 
> Ridgerunner is like an encyclopedia -- so helpful.


I would look around and call golf/turf suppliers who might have it. SOP prices here is around 25-30 for a 50lb bag. You're on the right track of keeping the S into account as well.


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