# Confused about the numbers N-P-K



## Sidney (Jun 12, 2017)

I thought if I got 46-0-0 or 39-0-0 my grass would EXPLODE with green! But today when I went to Site One, I asked for 39-0-0 or anything with x-0-0. Every time I go there, they always either tell me they don't have any or I don't need that. Today, the guy asked why I needed it. I told him that I scalped my bermuda and I want it "energize it". He said that he has 21-0-0 but it's still not what I need. He said I need either 24-2-11 or 34-3-11. I said okay, giving in to the "pro", I got 34-3-11.

As he was loading the bag in my trunk, he said the higher the first number is, is the amount of area it will cover. He said 39-0-0 will do the same thing 15-0-15 would do.

I have always known the numbers were for the amount of Nitrogen, Phosphate and Potash. And had NOTHING to do with coverage area.

His explanation sounded STUPID to me but what do I know. So, to my real pros here, can you clarify the numbering and what he said?

Sidney


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## J_nick (Jan 28, 2017)

No 39-0-0 and 15-0-15 are not the same. Those are the NPK numbers. Now a 39-0-0 and a 21-0-0 could be the same thing but you are buying more filler material. Let's just say the bag of fert is 100 pounds for simple math. The 39-0-0 you have 39 pounds of Nitrogen while the 21-0-0 only has 21 pounds of N. You would apply the 39 at 2.5 pounds per thousand and the 21 at around 4 pounds per thousand.

I guess you could say the higher the number on the bag the more ground it will cover since you will be applying a smaller amount. But you were correct. Those numbers are the percentage of N-P-K in the bag of fertilizer.


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## j4c11 (Apr 30, 2017)

39-0-0 is sulfur coated urea (the remaining 7 to 46 is the sulfur coating which adds weight to the bag and reduces the N percentage), and so even though the first number is large, the coating means the N gets released in a slow trickle as the coating breaks down. In your case, since you scalped, you're looking for a fast release fertilizer that will dump a lot of readily available N into the root zone to trigger a growth surge, so 39-0-0 is not the right product. Looking at the label for 34-3-11, it's 80% water soluble nitrogen, so it looks like his guidance was appropriate in this case.


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## Mightyquinn (Jan 31, 2017)

Hey Sidney, I use to be stuck on the whole xx-0-0 numbers for fertilizer but through reading and research, it's actually not a bad thing to have a little K in the mix(xx-0-xx) as Potassium is probably used up by the grass right behind Nitrogen and is/can leech from the soil relatively easy like Nitrogen can. Usually going with the highest nitrogen number you can get will give you the most bang for your buck.


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## wardconnor (Mar 25, 2017)

That dude at the store is stupid. He has no idea what he's talking about. Trust the knowledgeable people on TLF and just keep quiet when you shop.


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## Mightyquinn (Jan 31, 2017)

wardconnor said:


> That dude at the store is stupid. He has no idea what he's talking about. Trust the knowledgeable people on TLF and just keep quiet when you shop.


Not a bad idea but you could also just ask what they have in stock or ask to go out into the warehouse and look around to see if something catches your eye. Don't feel like you are "forced" to buy anything either as I doubt they will care either way if you buy something or not.


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## Iriasj2009 (Feb 15, 2017)

When I go buy ammonium sulfate 21-0-0, they always ask me what I am trying to do. I just politely tel them to just let me know if they have any or not and then proceed with how much do I owe you lol.


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## dfw_pilot (Jan 28, 2017)

Iriasj2009 said:


> When I go buy ammonium sulfate 21-0-0, they always ask me what I am trying to do. I just politely tel them to just let me know if they have any or not and then proceed with how much do I owe you lol.


+1. When going to places like Site One or other places used to dealing with pros, it's always best to do your research prior to entering the store. Whatever you do, don't do your research in front of the salesman.

Also, when buying homeowner amounts of something, always call ahead so you can go to the store that has what you need. If they don't have it, they'll try to sell you something you don't need.

Bottom line: Research here on TLF for what you need, and then use pro places like SiteOne to buy anything exotic that you may want.

Fast release (21-0-0) is good for quick energy and healing from a scalp. Slow release (39-0-0) is good for maintenance.


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## j4c11 (Apr 30, 2017)

I've had the same experience with SiteOne. I went and asked for something with a very high percentage of poly coated urea and they brought back a bag of product which was 80 water soluble urea. Either they don't know, don't care, or think they know what you need better than you do. I learned my lesson, I go dig up the appropriate product on their website, call to see if they have it, then go get it.


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## Mightyquinn (Jan 31, 2017)

I haven't been to my Site One in a couple of years but they were usually pretty nice and helpful with stuff and not pushy at all. They are the ones that introduced me to Celsius and the rest is history as most of you all know already. 

I think it also helps if you go in there a lot more than once a year as they will know your face and be more likely to help you than to push a product on you. I use to like the old website they use to have as you could look up what they had in stock before you went. They were always surprised when I asked for something and they were like "hey, how did you know we had that?"


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## Redtenchu (Jan 28, 2017)

A similar thing happened to my brother Friday at a local farm store, thankfully he called me. Long story short, he spent his money at a different store.


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