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Ferrous Ammonium Sulfate | Liquid Iron for Lawns

255686 Views 875 Replies 184 Participants Last post by  corneliani
I've been using this solution for many years with pretty good success on my Tifway lawn. This stuff is similar to the Iron sprays you can buy but it is much cheaper to make it yourself and the products are easily available on eBay. Spraying this solution will help give your lawn a deeper darker green and will generally last a few weeks. This is what you will need.

Ferrous Sulfate(Iron)

Ammonium Sulfate

One of THESE will come in handy to mix it all together.

For every 1K of lawn you will want to mix 4oz of Ferrous Sulfate, 3.4oz of Ammonium Sulfate in 1 Gallon of water. I usually mix it in a 5 gallon bucket of HOT water as it will dissolve faster and easier than it will with cold water. In that 5 gallon bucket, I will mix everything for 8K of lawn in one shot and then dilute it in the sprayer tank.

You will want to spray this in the evening when it isn't as hot outside to reduce the chance of burning your lawn(I have never had an issue with it). You will want to leave it on your lawn for as long as you can. I usually spray it the night before my irrigation is set to go off. I have gotten into the habit of mixing this with my PGR app every 3 weeks as it seems to be perfect timing for applying the stuff.

I wouldn't worry about the 21-0-0 in the Ammonium Sulfate as you are applying such a small amount that it shouldn't have any effect on your overall Nitrogen applications. The Ammonium Sulfate is in the solution to help give it a faster and more intense green up and CAN be omitted if you choose. I have never sprayed without it so YMMV(Your Milage May Very).

The Ferrous Sulfate is the MAIN ingredient for the dark green color.

The Ammonium Sulfate basically acts as a booster for the Ferrous Sulfate and will enhance/speed up the greening process.

Ferrous Ammonium Sulfate for every 1K of Bermuda Lawn
4.0 oz of Ferrous Sulfate (0.8oz of Fe)
3.4 oz of Ammonium Sulfate
1 Gallon of Water(preferably Hot or Warm)

Ferrous Ammonium Sulfate for every 1K of Cool Season Lawn
2.0 oz of Ferrous Sulfate (0.4oz of Fe)
1.7 oz of Ammonium Sulfate
1 Gallon of Water(preferably Hot or Warm)
Avoid the iron on the leaves in summer temperatures.

Edits: add cool season rates to avoid a black lawn.
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I was planning to spray an AMS app (0.25N/K) and just wondering if I can just add 2oz iron to that? My main concern is that it im watering in the AMS right away to prevent burning (and because I actually need to do a soil app to start lowering ph and increase sulfur but dont have granular) will I lose the effect of iron by washing it out ?
Avid123 said:
I was planning to spray an AMS app (0.25N/K) and just wondering if I can just add 2oz iron to that? My main concern is that it im watering in the AMS right away to prevent burning (and because I actually need to do a soil app to start lowering ph and increase sulfur but dont have granular) will I lose the effect of iron by washing it out ?
No wrong way to doing this, but the 2oz rate of Ferrous Sulfate is really a foliar amount. I think that's where you get the biggest/best effect. Once you wash it into the soil ecosystem you're essentially leaving it to the plant to do its thing, whereas foliar apps can act as a bit of an IV into the plant
2
I conducted my experiment last night:

Municipal water supply pH 9.4

1 Gallon Water, 2oz Iron, 1.7 oz AMS, 1/8 tsp CA.
Mixing order: Water, AMS, CA, Fe

pH of water after AMS and CA, 5.8.

Color of mix was good. It wasn't as good as some member's deep green but definitely convinced it was not orange.

I sprayed and let it sit overnight - rinsed off with 0.10 inches of irrigation in AM.

Obviously left side of front yard received iron.


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TheZMan said:
Color of mix was good. It wasn't as good as some member's deep green but definitely convinced it was not orange.
Yeah, looks good. If you are comparing to my mix, mine was _really_ concentrated in the bucket in the photo, prior to dilution in the sprayer.
I've skimmed through this topic and used the search but haven't found anything about using liquid ferrous sulfate like the one in the picture. Would this work instead of the soluble powder?
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I would be concerned with the other ingredients:

Per an answer in Amazon:
1tsp. Contains 220 mg Ferrous Sulfate providing 44mg of elemental iron. Other ingredients are citric acid, FD and C yellow #6, flavor, sodium benzoste, sucrose and water.

It also seems extremely expensive. Your post remind me that I need to buy more, so i just ordered this:

Alpha Chemicals Ferrous Sulfate Heptahydrate - FeSO4*7H2O - 20% Iron - Very Soluble - 5 Pounds https://a.co/d/2mm4Jj3

The price per pound seems good.
I just noticed you have an acre. You don't want to buy this at Amazon for that amount of lawn.

Do you have a reinders close by? This 50lb bag is $20.

https://www.reinders.com/products/450-1399/
Thanks. Right now I'm only treating the 2500sq ft in the front yard I renovated. I wasn't sure since this was in a liquid form if the rate would be lower around 1-2oz/1000. I ended up grabbing some 15-0-0+6% from tractor supply.
So I have been spraying (what I think) to be a version of a FAS solution over the past two seasons- I am running out of my nitrogen source and decided to revisit this thread to decide what I will replace it with. After reading through 43 pages, I'm not sure which way is up, and looking for clarity on this situation:

I currently spray a mixture of Main Event Iron @ 2oz/1k (effectively my Ferrous Sulfate source) along with The Anderson's Humic Coated Urea @ 0.6lbs/1k (.264N/1K)(effectively my nitrogen source) mixed in with my bi-weekly PGR apps. I have never measured PH and my normal solution is a dark orange/black color (mostly due to the Humic).

I'm not sure why one would continue to utilize the FS in the OP when Main Event contains micros, chelated iron, won't stain concrete, etc? This makes me feel like I am missing something.

Should I replace the urea in this mixture with some form of AS + citric acid for better results? I've seen both yays/nays in this thread.

Or, should I continue with my current mixture of Main Event + Urea, and just lower water ph with citric acid?

Here is a recent soil sample, if this helps. You can see the effect of Main Event with the levels of micros & Fe in the yard:

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@bri831 - definitely just stick to the recipe here to save money.

https://turf.unl.edu/turfinfo/6-7-Iron-Chelates.pdf#:~:text=If%C2%A0iron%C2%A0,or%C2%A0burn.

Read bullet points 1, 2 and 3 :)

I think g-man has brought this article up a bunch of times. I'll never spend money on an iron product thinking it will outperform regular iron when (due to my pH) foliar uptake is my goal.
Has anyone experimented with higher rates of AS when doing this?

My math says...2oz/gal of AS nets very light N..or 0.02lb N

I see guys spraying 1 lb AS (16oz) / gal/1000 for foliar apps of feeding, puttine 0.20 lb n to leaf.

SO.....I was thinking to increase my FAS mix to AS 6oz-8oz/gal/1000 for a Net of 0.08 - 0.10 lb N foliar.
anyone have a problem with that?
You can do that. But be careful with your carrier rate using AMS. To me 0.25N of AMS in 2g/ksqft to avoid white tip leaves and do a quick irrigation cycle after 4hrs.
ive been doing it @ 2.5 oz/gal/1000 AS for a while, sometimes jacking it up to 4oz/gal/1000 in spring -fall..with better results.

I juggle around the FE rate....never an issue--and learned to lay off in the heat 2-3 years back.

I never spray over 85f.

I sprayed yesterday, and it dawned on me, Im too light on AS. I do get results at 2.5, but its soo light on N.
Im Not looking to jack it to 8oz yet, but that still seems quite safe....(see pic) -even though that turf pro is using Urea.
I used that Turf pro blade Iron about 4 years back, works Awesome, but your buying water shipped.....thus I also went to FAS....dirt cheap.

Gman, I am not sure what you mean on carrier rate. I am also generally less than 1 gal per 1000 anyways..as a added safety margin with the tip im using.

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Carrier rate = volume of water over a specified area. Generally it is 1 gallon per 1000 sq ft for majority of stuff we use for our lawn. At .08 - .10 lb of N via AS, you should be safe at your carrier rate of "less than 1 gal per 1000". Higher carrier rate uses more water so it will require higher spray rate or doing a double pass to get the same coverage as a low carrier rate, but that will allow better coverage and less risk of over application.
got ya! yes, Im pretty conservative on that. And yes, double passing with lower rate has advantages, except you get more tired....LOL.

I plan on raising my AS to 6-8 oz/gal/1000 from 2-4oz.

I do run around 4-5 oz iron. i dont want to push that much more...that iron has its limits as well.

Yesterday I sprayed 2 oz/4oz. Fas....and it was nearly a instant response. My turf is very hungry and it got hammered in the last few weeks with 95-99f and no rains for a long time. so i went easy. First spray since may. I got alot of work to do..LOL........

No overseeding here......im going to be Mr Nitro.
I'm getting lost between AS, FS and FAS oz rates in the last posts.

I think the main benefit of a higher carrier rate is less concentrated drops on the leaves. AMS lowers the pH of the water and at high concentrations it can cause some damage.

If desired, you can mix in this order: water then AMS (and CA), then FS and then add urea (or DEF). This is what I normally do in the summer (but below 85F).
Ammonium sulfate by nature is always 21-0-0 correct? So the amounts on the very first page is agnostic to what brand is purchased correct?
Has the use of a surfactant been discussed for better distribution on the leaf blades ?

I was planning on using some dawn soap with my next app

Just curious if anyone had tried this

The thought is, insteqd of 1 big bead on the leaf, the FAS is spread out which gives it more sites to be absorbed
I use an XR Teejet nozzle for my Tnex and FAS apps (2oz Fe for cool season). This last time I used NIS at 2tsp per gallon and that was the darkest I have ever seen the lawn. My anecdotal findings are that I will try it with a NIS again.
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