# Elemental Sulfur Application Rates on Cool Season Turf



## Jim[9] (Jun 13, 2020)

Hello! I have a cool season mixture of mostly KBG but there is also a small mixture of TTTF in the back yard mixed in. I am looking for some opinions on the application rates for elemental sulfur. I have a pH of 7.5 and a Sulfur level of 14 ppm. The main issue I have is where the turf just isn't responding to fertilizer applications that well, particularly in the summer when I'm not pushing the turf that much I can really see the color backing out of it.

Working with the master gardener from the county extension office it has been suggested to apply 10-lbs/1000 sq. ft. immediately (before we emerge out of winter dormancy here), otherwise do 5-lbs/1000 and another 5-lbs/1000 at the end of the summer.

Does anyone have any opinions on application rates here? I've read a lot of mixed articles where some have said 10-lbs/1000 is fine at one (and would be an annual limit, consistent with the advice I was given), bur there are a lot of other articles out there suggesting to not exceed 5-lbs/1000 in any single application, with a 10-lbs/1000 maximum annual limit.

What do you all think? The only concern I have is am I already too late? Last week we had some temps in the 70's and the soil temp barely reached 55. It got colder again this week so the soil temp is back down in the 40's, and we are projected to get 5" of snow tomorrow. Next week will be back up near 60-degrees though and sunny so I'd expect the snow not to stick around. There's a small section that gets some runoff from a hill and full sun that did "green up" from the small heat wave last week. Looking to get some opinions from others who have applied sulfur to and what the application rate was. Thanks!


----------



## bernstem (Jan 16, 2018)

I use 5 lbs/1000 2x per year. You are fine to drop now. Sulfur needs warm soil to convert to acid. Application at lower soil temps will sit in the soil until they warm up. If the ground has snow on it the bacteria to convert the sulfer will not be active.


----------



## Jim[9] (Jun 13, 2020)

Thanks for the reply! I've read about sulfur needing heat to break down.

Do you know where the application rates come from? Or the concept of why some sources recommend the two split apps of 5lbs/1000 versus one app of 10lbs/1000?

I'm wondering if since the turf is still dormant it can handle the 10lbs rate, whereas if it's starting to grow it can't?


----------



## bernstem (Jan 16, 2018)

Application at higher rates can result in a very low pH in the top layers of soil until it works deeper into the soil profile.


----------



## Jim[9] (Jun 13, 2020)

That makes sense. The master gardener said there would be a buffer as it works it's way down deeper into the soil.

I'm leaning towards the two applications because my turf looks good, I just know that some nutrients are locked into the soil. I feel this is causing me to over fertilize a bit to keep the color.

Any suggestions on timing the second application or temperature restrictions around it?


----------



## bernstem (Jan 16, 2018)

Apply when the temps start to warm up. Second application in mid/late summer depending on weather and temps.


----------



## Jim[9] (Jun 13, 2020)

bernstem said:


> depending on weather and temps.


Should I treat that second app like a herbicide, targeting a date where daytime temperatures are less than 85-degrees for a few days. Say a mild week in late July, August, or early September?


----------



## bernstem (Jan 16, 2018)

I don't know that temperatures matter for sulfur application like they do with a herbicide.


----------



## Jim[9] (Jun 13, 2020)

Alright, that's good to know.....thank you for the help!


----------



## Wile (Sep 17, 2020)

I agree with Bernstem. Split apps of 5lbs/M maxium 10lbs annually. I noticed mine didn't start breaking down until soil temps were around 65-75 degrees and consequently the second app seemed to break down much faster in August than the one I did in June. Which followed everything I read about the soil temps needing to be very warm in order for the microbes to convert it to sulfuric acid and beginning the pH reduction.


----------



## Deadlawn (Sep 8, 2020)

Jim[9 said:


> " post_id=464378 time=1647048764 user_id=10583]
> Hello! I have a cool season mixture of mostly KBG but there is also a small mixture of TTTF in the back yard mixed in. I am looking for some opinions on the application rates for elemental sulfur. I have a pH of 7.5 and a Sulfur level of 14 ppm.
> 
> Working with the master gardener from the county extension office it has been suggested to apply 10-lbs/1000 sq. ft. immediately (before we emerge out of winter dormancy here), otherwise do 5-lbs/1000 and another 5-lbs/1000 at the end of the summer.


7.5pH and they're recommending elemental sulfur, really? 7.5pH isn't all that high. If you look a the chart below, most nutrients are still available at 7.5:





Jim[9 said:


> " post_id=464378 time=1647048764 user_id=10583]
> The main issue I have is where the turf just isn't responding to fertilizer applications that well, *particularly in the summer when I'm not pushing the turf that much I can really see the color backing out of it. *


My guess is this is just summer die back/dormancy. Growth slows as summer rolls around and grasses go into a self-preservation mode. Feeding at this time will just stress the grass even more. You wouldn't want to be force-fed when you're not well, would you?


----------



## MNGooner (Oct 22, 2021)

Wasn't doing the maths too well and accidently put down ~8lbs/1000 sulfer in the front yard. Ph is 7.6 and soil temps are right around ~60. Wondering if I should water it in to correct for the over application or just let it ride and hope it breaks down slowly as soil temps rise? Appreciate any thoughts...at least I realized and corrected for the back yard.


----------



## Deadlawn (Sep 8, 2020)

MNGooner said:


> Wasn't doing the maths too well and accidently put down ~8lbs/1000 sulfer in the front yard. Ph is 7.6 and soil temps are right around ~60. Wondering if I should water it in to correct for the over application or just let it ride and hope it breaks down slowly as soil temps rise? Appreciate any thoughts...at least I realized and corrected for the back yard.


Yikes! Yes, water it in if there is no rain in the forecast.


----------

