# Fertilizer application in hot weather



## Movingshrub

Is there any kind of guidance on applying fertilizer in hot weather?

I am planning to apply granular ammonium sulfate at one pound of nitrogen per thousand square feet and then will water it in the morning. The day time high temp for the foreseeable future is above 90F. Thanks.


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## Redtenchu

Nope, just don't apply while the lawn is wet.


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## Spammage

I don't usually put down a heavy app (1 lb of N/k) during hot weather. It will cause drought stress earlier, and I don't want to spend any more time outside than absolutely necessary when its this hot.


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## jds912

what kind of grass?


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## Movingshrub

jds912 said:


> what kind of grass?


TifTuf Bermuda.

I've been putting down one pound of N per week to drive growth/filling-in on my sprigging project. Fortunately, every time I've applied fertilizer so far, the temperature has been in the 70s or low 80s. Today was the first time I've applied in the 90s. Also, in case it matters, I'm applying fast release style fertilizer. I also water it in the next morning if it doesn't rain that day.


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## Crimson2v

I did not know you can put out that much, does it really help the growth? My backyard has large spots where the bermuda did not come back after last years seeding. I don't want to hijack the thread but would that be a good idea?


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## Movingshrub

Crimson2v said:


> I did not know you can put out that much, does it really help the growth? My backyard has large spots where the bermuda did not come back after last years seeding. I don't want to hijack the thread but would that be a good idea?


Regarding the amount if N:
I think 1LB of Nitrogen per 1,000 SQFT is about the max rate per week.

I got my information from https://extension.tennessee.edu/publications/Documents/W160-D.pdf

and there is another document from Missouri that directs 0.5LB per 1,000 SQFT per week.

http://turf.missouri.edu/stat/reports/pdf/aggbermudagrowin.pdf

Depending on the size of the area, you may be better off plugging to fill it in.

Regarding my temp question, I went ahead and put down the fertilizer today, and it ended up raining a few hours later so hopefully I am in the clear.


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## jds912

I imagine your cutting interval will be every other day for a few weeks. Are you applying any other nutrition in between nitrogen apps.?
I would think with that much n put down the grass is draining its carbohydrate reserves. Maybe some potassium in between? What kind of soil, acidic or alkaline?


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## Movingshrub

jds912 said:


> I imagine your cutting interval will be every other day for a few weeks. Are you applying any other nutrition in between nitrogen apps.?
> I would think with that much n put down the grass is draining its carbohydrate reserves. Maybe some potassium in between? What kind of soil, acidic or alkaline?


I have been checking the pH and it seems to be staying around 6.5.

The documents I attached earlier involve a fertilizer schedule that also includes an all purpose fertilizer. I am applying 15-15-15 at one pound of N per thousand square feet every forth week.

Also, I put down a slow release starter fert at the time of planting.


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## jds912

i dont think the temp will have much to do with salt burn from fertilizer. i would tend to think you may lose some to evaporation before the grass can utilize the n. i imagine its filling in nicely with all the fertilizer? have you applied primo to the area?


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## slomo

You can fert all you want if you have Bermuda or its cousin Tif. It loves all the N you can afford to spend.

slomo


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## Movingshrub

jds912 said:


> i dont think the temp will have much to do with salt burn from fertilizer. i would tend to think you may lose some to evaporation before the grass can utilize the n. i imagine its filling in nicely with all the fertilizer? have you applied primo to the area?


I haven't applied primo. I was doing one pound of Nitrogen per thousand square feet every 3-4 days for the first three weeks, then switched to applying once a week. No one is using the space so I really have this entire growing season for it to get established.


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## Redtenchu

slomo said:


> You can fert all you want if you have Bermuda or its cousin Tif. It loves all the N you can afford to spend.
> 
> slomo


Tif is Bermuda, not a cousin.

Over application of Nitrogen is not only wasteful, but can be harmful to Bermuda due to excessive top growth.

The nicest Bermuda lawns on this forum are at a rate of 1lb/1k per month or less.


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## Movingshrub

Redtenchu said:


> slomo said:
> 
> 
> 
> You can fert all you want if you have Bermuda or its cousin Tif. It loves all the N you can afford to spend.
> 
> slomo
> 
> 
> 
> Tif is Bermuda, not a cousin.
> 
> Over application of Nitrogen is not only wasteful, but can be harmful to Bermuda due to excessive top growth.
> 
> The nicest Bermuda lawns on this forum are at a rate of 1lb/1k per month or less.
Click to expand...

Concur with normal application rate for an established lawn. I used the Univ of TN turfgrass guidance on amount of N for sprigging fill-in and also guidance from golf course superintendent. Once grass is established, the amount of nitrogen will go to a normal rate.


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## J_nick

+1 Movingshrub, for sprigging 1-2# N a week is what I researched too. For an established lawn 1# N every 4-6 weeks.


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## Movingshrub

J_nick said:


> +1 Movingshrub, for sprigging 1-2# N a week is what I researched too. For an established lawn 1# N every 4-6 weeks.


I hadn't seen anything suggesting 2LB a week. If I had know that imagine the full rate I could have been pushing. My understanding is that I was actually limited by sunlight, this time of year, vs the amount of nitrogen.


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## slomo

Talking about fill-in areas, dead spots and such. More N you spread the more grass and mowing. Faster way to fill in areas in need.

slomo


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## Movingshrub

slomo said:


> Talking about fill-in areas, dead spots and such. More N you spread the more grass and mowing. Faster way to fill in areas in need.
> 
> slomo


In my case, I had planted by way of sprigging; my entire yard was the fill-in area. If it was one spot, that would be a different story potentially.


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## Movingshrub

J_nick said:


> +1 Movingshrub, for sprigging 1-2# N a week is what I researched too. For an established lawn 1# N every 4-6 weeks.


Have you ever seen any documentation to the max amount of nitrogen that can be fed to Bermuda? My theory is that the answer may be related to the amount of sunlight being received at the time of year/length of day.


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## J_nick

Movingshrub said:


> J_nick said:
> 
> 
> 
> +1 Movingshrub, for sprigging 1-2# N a week is what I researched too. For an established lawn 1# N every 4-6 weeks.
> 
> 
> 
> Have you ever seen any documentation to the max amount of nitrogen that can be fed to Bermuda? My theory is that the answer may be related to the amount of sunlight being received at the time of year/length of day.
Click to expand...

Not that I can remember.

This is just my opinion but I don't even think the Bermuda can use all the 1-2#s a week. With as frequently you have to water with sprigging I would think some would leach away or volatilize before being takin up by the plant especially at the higher end.


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## Movingshrub

J_nick said:


> Movingshrub said:
> 
> 
> 
> 
> 
> J_nick said:
> 
> 
> 
> +1 Movingshrub, for sprigging 1-2# N a week is what I researched too. For an established lawn 1# N every 4-6 weeks.
> 
> 
> 
> Have you ever seen any documentation to the max amount of nitrogen that can be fed to Bermuda? My theory is that the answer may be related to the amount of sunlight being received at the time of year/length of day.
> 
> Click to expand...
> 
> Not that I can remember.
> 
> This is just my opinion but I don't even think the Bermuda can use all the 1-2#s a week. With as frequently you have to water with sprigging I would think some would leach away or volatilize before being takin up by the plant especially at the higher end.
Click to expand...

At the beginning irritation is constantly, however by week 4, you move to a more normal schedule. I am almost to 11 weeks since I planted but I am a still trying to push the fill in of the Bermuda. I've been doing 1LB of N a week and irrigating to supplement rain and to water in fertilizer when necessary.

I know the days are getting shorter know, but I wish I knew whether my limiting factor was sunlight, water, or nutrients.


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## slomo

You can fert Bermuda every week if your wallet allows. 46-0-0 all you want. You will me mowing your butt off and the yard will fill in and get super thick. What's not to like? If I had a small yard like most folks, I would fert bi-monthly at least. Just water it in and read the bag of course. There has been zero cases where someone over ferted their Bermuda lawn, and killed it.

slomo


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## thegrassfactor

J_nick said:


> Movingshrub said:
> 
> 
> 
> 
> 
> J_nick said:
> 
> 
> 
> +1 Movingshrub, for sprigging 1-2# N a week is what I researched too. For an established lawn 1# N every 4-6 weeks.
> 
> 
> 
> Have you ever seen any documentation to the max amount of nitrogen that can be fed to Bermuda? My theory is that the answer may be related to the amount of sunlight being received at the time of year/length of day.
> 
> Click to expand...
> 
> Not that I can remember.
> 
> This is just my opinion but I don't even think the Bermuda can use all the 1-2#s a week. With as frequently you have to water with sprigging I would think some would leach away or volatilize before being takin up by the plant especially at the higher end.
Click to expand...

If you apply 1lb of quick release N, you'll lose almost immediately 1/4lb to volitalization. Where you run into upper limits of N applications is the salt index of your N source. Salt burns. That's why fert burns. If you run a super low salt index fert like methylene urea, go to town. It just release soooo slow there's not much color response


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## BXMurphy

Movingshrub said:


> Is there any kind of guidance on applying fertilizer in hot weather?


You would typically put down Milorganite during late spring and through summer. Then do a fall nitrogen blitz with urea. Both are fairly inexpensive and will treat you well.

Milo is 85% organic matter (yummy) and 5% slow-release nitrogen. It requires microbial action to release the nitrogen. Don't have microbes? The organic matter will feed and grow whatever you have.


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## Ware

BXMurphy said:


> ...Then do a fall nitrogen blitz with urea. Both are fairly inexpensive and will treat you well.


No "Fall Nitrogen Blitz" on warm season lawns. :no:


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## Movingshrub

thegrassfactor said:


> If you apply 1lb of quick release N, you'll lose almost immediately 1/4lb to volitalization. Where you run into upper limits of N applications is the salt index of your N source. Salt burns. That's why fert burns. If you run a super low salt index fert like methylene urea, go to town. It just release soooo slow there's not much color response


If it matters regarding volitizarion, I am irritating the next morning following application of granular ammonium sulfate.

TGF, I want to make sure I am following you correctly. It's the salt that burns, not necessarily the amount of nitrogen itself applied, correct?

So, if I were to apply urea in lieu of ammonium sulfate, would I be able to apply a greater quantity of nitrogen to the turf without burn, since urea has a lower salt index that ammonium sulfate?

Maybe I should reframe the question to be - what is the max amount of nitrogen, and type of nitrogen that can be applied, in order to maximize lateral growth, without burning Bermuda turf? Lastly, does the answer vary based on temperature, amount of sunlight, amount of water, soil type, growing degree days, etc., or some other variable I hadn't considered?


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## BXMurphy

Ware said:


> No "Fall Nitrogen Blitz" on warm season lawns. :no:


Good grief! What do warm season lawn people do for fun with lawns?

'Course... having a lawn year 'round would be fun, now that I think of it... <sigh> Never mind...


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## thegrassfactor

Movingshrub said:


> thegrassfactor said:
> 
> 
> 
> If you apply 1lb of quick release N, you'll lose almost immediately 1/4lb to volitalization. Where you run into upper limits of N applications is the salt index of your N source. Salt burns. That's why fert burns. If you run a super low salt index fert like methylene urea, go to town. It just release soooo slow there's not much color response
> 
> 
> 
> If it matters regarding volitizarion, I am irritating the next morning following application of granular ammonium sulfate.
> 
> TGF, I want to make sure I am following you correctly. It's the salt that burns, not necessarily the amount of nitrogen itself applied, correct?
> 
> So, if I were to apply urea in lieu of ammonium sulfate, would I be able to apply a greater quantity of nitrogen to the turf without burn, since urea has a lower salt index that ammonium sulfate?
> 
> Maybe I should reframe the question to be - what is the max amount of nitrogen, and type of nitrogen that can be applied, in order to maximize lateral growth, without burning Bermuda turf? Lastly, does the answer vary based on temperature, amount of sunlight, amount of water, soil type, growing degree days, etc., or some other variable I hadn't considered?
Click to expand...

The only thing you could do to mitigate the volatilization would be to tie it up with carbon, a la humic acid or biochar. once the water hits it and it goes into solution, the loss takes place. the reaction with water is going to create small amounts of gas. upwards of 34% of the total nitrogen is lost. is this improved with urea? no. the same thing will take place. it doesn't work quite the same way, but the loss will mostly occur due to leaching because the urease has to aide in the conversion of urea to usable nitrogen, and that will take an amount of time. plus, once urease reacts with urea, a gas is formed, which too is open to loss.

in regards to the salt index, urea and ammonium sulfate aren't that far off from each other, so i wouldn't get too hung up that one is better than the other. if you're looking for a quick blast, i prefer ammonium sulfate. the sulfur is a consumed nutrient so supplementation isn't a bad thing. besides, if you look at the composition of sulfur - so4 - that's 4 parts oxygen to 1 part sulfur. so you're introducing quite a bit of oxygen to the soil surface which is good forsoil microbes to move there and work.

the final thing to take into consideration is exactly how much N will the bermuda actually use. and there are a 1000 different answers to this because, as you said, it is dependent on sunlight, soil moisture, soil composition, etc. if you're weekly feeding, i would go 1/4lb to 1/2lb personally, and apply it in conjunction with humic acid. the carbon will tie up the N and help loss due to volatilization. plus, carbon is great for the soil.

there is also some research being done with microdosing bermuda yearly (less than 3lbs total N per year being applied with humic acid, kelp, and micros). the odd thing is, it's still stimulating the lateral growth without stimulating the stem elongation. what you're left with is more visible leaf tissue, and ultimately better color with less mowing. but this is still super super early at UGA and 4 years away from any sort of publication.


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## Josh846

Thegrassfactor I know this is from 20q7, but do you know anymore about the research. You said it would be 4 years before anything is published.


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