# SOP vs MOP - Cost premium



## HomerGuy (Jun 5, 2017)

According to my soil test it is deficient in both P & K. Waypoint recommended adding 5lb of K.

I know that SOP is preferred to MOP. I have found both products, but the cost difference between them is pretty significant. SOP is $32 per bag and MOP is $13.50 per bag. If I only needed a couple bags I would just go with the SOP, but with the size of my yard and the amount I need, the extra cost for the SOP adds up quickly.

Can I go cheap on this one and get the MOP or should I bite the bullet and spend the extra for the SOP?


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## Suburban Jungle Life (Mar 1, 2018)

You can use MOP. The majority of fert blends have MOP. They just don't have a ton of it compared to the N so you really aren't using a lot. If you're trying to add 5lb of K, is that per 1000 sq ft? MOP has a much higher salt index than SOP. Too much at once can kill the grass. Make sure you do plenty of watering or lots of rain. Of course, not to the point of runoff. If you don't irrigate, spring would be the best for more of it since it rains more. Fall would be next. I wouldn't put it out in the summer. If you really feel like getting it out now, wait for a rain forecasted the next day and put down a low rate each rain until fall.


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## HomerGuy (Jun 5, 2017)

Ok thank you. Yes the 5lb of K is per 1000 sq ft. I don't think I will be able to get it all down this year, but wanted to try and make a dent in it at least.

I was thinking of putting down 0.5-1.0 lbs of K per month so 0.8-1.6 lbs of MOP per thousand per month.


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## Ridgerunner (May 16, 2017)

In addition to the high salt index concern, turf uses very little chlorine (so little that it is not listed as a micro-nutrient), but turf does use sulfate. SOP supplies sulfate, MOP dosen't. If your soil is low on S, you may want to consider a combination of SOP and MOP?


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## social port (Jun 19, 2017)

I've been using MOP this year. There has been no damage from the applications, as far as I can tell.
I use very light rates--about .25 lb/k. Honestly, that is overly cautious, but that is what I do.
With a rate so light, I had to buy a handheld spreader. 
Of course, I always water ASAP or let (hopefully gentle) rain do the work for me.


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