Ferrous Ammonium Sulfate | Liquid Iron for Lawns

255666 Views 875 Replies 184 Participants Last post by corneliani, 3 d ago

Mightyquinn

Discussion Starter · Apr 25, 2017

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.

See less See more

Reactions: 2

821 - 840 of 876 Posts

corneliani

· #821 · Apr 29, 2022

john5246 said:
TheZMan said:

I got a bag off Amazon from the link in the beginning. It's greenway biotech. The bag says Ferrous Sulfate. It doesn't say Hepatahydrate. Same thing or no? Seller advertised as Hepatahydrate.

Click to expand...

can you put a link to that? I can't seem to find it. Based on the 5lb bag price I would imagine the 25lb bag is 1000 bucks?

Or buy from your local turf supplier. It may not be as 'refined' of a grade but you don't need it to be for turf. Some of these products are meant for hydroponics and other very sensitive applications & they don't require as much product, so that 5# goes a long way.
Heres SiteOne's Ferrous Sulfate, $30/50#bag (with an account).

See less See more

TheZMan

· #822 · Apr 29, 2022

I had a question regarding the stability of the FAS in alkaline water. I read in detail a few pages back guys stating their mix turns orange (oxidizes), and some said their results weren't great. My municipality supplies water around a pH of 9.0 (crazy)

I picked up a pH meter on Amazon and want to solve this issue for myself or cool season.

Plan is 1 gallon water per 1K sq ft:
2oz Ferrous Sulfate
1.7 oz AMS

I want to use Citric Acid but since it's so acidic it scares me. Can I get some guidance on a target water pH that would be safe for an overnight application of FAS + CA?

Order of mixing would be: Water, AMS, CA, Fe.

I'm not sure if I need to go this extreme but I know some guys on here were spraying really nice blue/green stuff and I don't want to haphazardly add too much acid to my water.

See less See more

g-man

· #823 · Apr 29, 2022

I do water, ca, ams and fs at the end. For how much ca, use your pH meter. The goal is to have it between 5 and 7 ph.

San

· #824 · Apr 29, 2022

I would keep it under 6pH, as above that citric acid won't be a stable chelator.

However if you mix it water, ca, ams, and measure around 7 with the ca, the ams will most likely take it down low enough to keep it under 6. So it depends on when you measure.

For reference this dates back to an old patent from 1955, the explanation and used these ratios:

Together with ferrous sulfate, we use citric acid principally by reason of its apparent eifectiveness as a chelating compound for solubilized iron, and for the further benefit of lowering to a desirable level the pH of high alkaline soils. When used even in relatively small proice portions, citric acid chelates the iron so effectively that when the combination ofmaterials is dissolved andintroduced to the soil, the iron is retained by the chelation for assimilation by the plants over a period of time well beyond that at which the iron could remain so available in the absence of the citric acid.
The third essential ingredient of the present composition is ammonium sulfate, which is used for the dual purposes of increasing the chelation effect of the citric acid, as by the formation of a complex of the salts having. chelative relation to iron, and for the further purpose of making available nitrogen which becomes assimilable by the plant by virtue of its acceptance of the iron.

Ratios:

1. A soil conditioning material consisting essentially of ammonium sulfate, ferrous sulfate and citric acid in the proportions of about 1 weight part of ammonium sulfate, from 2 to 7 parts of ferrous sulfate and from 0.12 to 0.8 part of citric acid, iron contained in said ferrous sulfate being chelated by the citric acid and retained as unprecipitated iron in aqueous solutions of said material.
2. A soil conditioning material consisting essentially of ammonium sulfate, ferrous sulfate and citric acid in the proportions of about 4.6 weight parts of ammonium sulfate, 22.75 parts of ferrous sulfate and 1 part of citric acid, iron contained in said ferrous sulfate being chelated by the citric acid and retained as unprecipitated iron in aqueous solutions of said material.

Source: https://patents.google.com/patent/US2813014A/en

See less See more

mamoore9

· #825 · May 12, 2022

Is it possible to lessen the amount of water in the dilution mixture? I have a large lawn and having to refill a 4gal sprayer 4 times for 16k+ sqft sounds annoying.

Dkrem

· #826 · May 24, 2022

I use about a cup of citric acid per 20 gallon load in my sprayer to acidify my high pH Kentucky water. I've not measured the result pH, I just messed with 5gal test batches and scaled up when it stopped oxidizing. To that I add around 8 pounds of ammonium sulfate, and then 5-ish pounds of ferrous sulfate. I mix that all up, in order, in a 5gal bucket of hot water, then I decant it off the trash that doesn't dissolve and dilute it in the sprayer with straight hose water to final volume. I spray all that on ~3/4 acre.

EDIT: I mixed up and sprayed a batch last night, here's the concentrate as described above in my bucket:

See less See more

CaffeinatedLawnCare

· #827 · May 24, 2022

So I mixed up some FAS the other day (along with some PGR which turned the mixture orange /facepalm so I'm not sure if it stayed yellow/green after I dumped it into the full 2 gal tank).

Used the following rates per gallon of water:

1 tsp citric acid
1.7oz AMS
2oz FS

My initial water pH was a 7.6-7.8 (using pH strips that go from 6.2-9 - pool testing strips) and after adding the 1 tsp of citric it was definitely below the 6.2 (off the chart so hard to say what the actual pH was ...).

My question is, how much citric is actually needed? I saw a few different comments while reading through this entire thread and one suggested around 1:14 CA:FS and one suggested around 2:1 CA:FS ...

1:14 puts me at about the 1 tsp (which is what I tried because the other seemed so high at 4oz CA to 2oz FS?).

Which of these rates is correct?

Edit: Mixed the ingredients into a graduated bucket with 2 qts of water, then dumped that mixture into the other 1.5gal so 2gal total mixture at the end.

Image of the mixture with the 1 tsp rate of CA (1:14 CA:FS ratio):

See less See more

grumpsterfire

· #828 · May 27, 2022

Until today I'd just happily been spraying the orange/brown stuff.

The internet says rainwater is slightly acidic so I filled two 5 gal buckets of water from the downspout (very slight brown tinge) rather than from the tap for today's application. The result after adding AS then FS was no discernable orange color. The mix was cloudy white or slightly tan/gray.

This could be an alternative to CA for keeping your FAS app from turning orange / brown in the bucket.

TampaBayFL

· #829 · 12 mo ago

CaffeinatedLawnCare said:
So I mixed up some FAS the other day (along with some PGR which turned the mixture orange /facepalm so I'm not sure if it stayed yellow/green after I dumped it into the full 2 gal tank).

Used the following rates per gallon of water:

1 tsp citric acid
1.7oz AMS
2oz FS

My initial water pH was a 7.6-7.8 (using pH strips that go from 6.2-9 - pool testing strips) and after adding the 1 tsp of citric it was definitely below the 6.2 (off the chart so hard to say what the actual pH was ...).

My question is, how much citric is actually needed? I saw a few different comments while reading through this entire thread and one suggested around 1:14 CA:FS and one suggested around 2:1 CA:FS ...

1:14 puts me at about the 1 tsp (which is what I tried because the other seemed so high at 4oz CA to 2oz FS?).

Which of these rates is correct?

Edit: Mixed the ingredients into a graduated bucket with 2 qts of water, then dumped that mixture into the other 1.5gal so 2gal total mixture at the end.

Image of the mixture with the 1 tsp rate of CA (1:14 CA:FS ratio):

I did something similar last week. I wimped out and used 2 gallons of hot water and 4 oz FS and ~4 oz AMS, plus 1/4 tsp of CA. The water stayed light green even though my starting pH was off the charts (something in the 8's). After the 1/4 tsp of CA is was too low of a pH for me to measure (below 6).

I sprayed this on some test areas and even a few days later there is no discernible color difference on Citra Blue or Bermuda. I sprayed one area in particular HEAVY and I could see some slight damage but nothing horrible.

TampaBayFL

· #830 · 12 mo ago

Yesterday, I tried a different (even more gentle approach since I am being cautious) and over ~1750 sq ft of Citra Blue I used 0.6 oz (2 TBSP) FS, 0.6 oz (2 TBSP)AMS and 1 oz of liquid (palm) micros in 32 oz of sea kelp and sprayed it all through a hose end sprayer at a 2oz/gal rate. Well see if I notice anything with this concoction. I doubt it as its sooooo weak.

With my high pH, I dont believe the iron has much effect unless its foliarly applied. That said, I did burn the [email protected]$$ out of my Zoysia last year when I overapplied iron foliarly with not enough water as the carrier.

g-man

· #831 · 12 mo ago

TampaBayFL said:
Yesterday, I tried a different (even more gentle approach since I am being cautious) and over ~1750 sq ft of Citra Blue I used 0.6 oz (2 TBSP) FS, 0.6 oz (2 TBSP)AMS and 1 oz of liquid (palm) micros in 32 oz of sea kelp and sprayed it all through a hose end sprayer at a 2oz/gal rate. Well see if I notice anything with this concoction. I doubt it as its sooooo weak.

With my high pH, I dont believe the iron has much effect unless its foliarly applied. That said, I did burn the [email protected]$$ out of my Zoysia last year when I overapplied iron foliarly with not enough water as the carrier.

You can't do a foliar application with a hose end sprayer.

TampaBayFL

· #832 · 12 mo ago

g-man said:
TampaBayFL said:

Yesterday, I tried a different (even more gentle approach since I am being cautious) and over ~1750 sq ft of Citra Blue I used 0.6 oz (2 TBSP) FS, 0.6 oz (2 TBSP)AMS and 1 oz of liquid (palm) micros in 32 oz of sea kelp and sprayed it all through a hose end sprayer at a 2oz/gal rate. Well see if I notice anything with this concoction. I doubt it as its sooooo weak.

With my high pH, I dont believe the iron has much effect unless its foliarly applied. That said, I did burn the [email protected]$$ out of my Zoysia last year when I overapplied iron foliarly with not enough water as the carrier.

Click to expand...

You can't do a foliar application with a hose end sprayer.

I should have been more clear that I definitely understood that. I implied I was being a mega wimp 🤪since I didn't want to burn anything, and my main reason for using the hose and sprayer was to put down the kelp. I just threw the other stuff in for yucks. The previous test I did which showed no effect, and even light damage in an area where I applied it super super heavy, leads me to believe things may already be as good as they can get.

CaffeinatedLawnCare

· #833 · 12 mo ago

I didn't have any issues and it seemed to get pretty dark green (especially for my back lawn which is just a bunch of random grass types) so I know it is working. I got some better pH strips that read from 4.5-10 pH. I'll be able to check exactly how much CA it takes to get me below 5 pH.

Jonslawn

· #834 · 12 mo ago

Just mixed up my FAS with a couple tsp of citric acid. I wanted to apply it when it was raining lightly as I was afraid the citric acid would burn my grass without watering in. Can I still apply in the rain an still get the dark green effect or no if it's not sitting on the blades long at all?

frekwentflier

· #835 · 12 mo ago

Jonslawn said:
Just mixed up my FAS with a couple tsp of citric acid. I wanted to apply it when it was raining lightly as I was afraid the citric acid would burn my grass without watering in. Can I still apply in the rain an still get the dark green effect or no if it's not sitting on the blades long at all?

I doubt this would work. I believe the best approach is to spray FAS on the day before, then water in the next morning.

Jagermeister

· #836 · 12 mo ago

Jonslawn said:
Just mixed up my FAS with a couple tsp of citric acid. I wanted to apply it when it was raining lightly as I was afraid the citric acid would burn my grass without watering in. Can I still apply in the rain an still get the dark green effect or no if it's not sitting on the blades long at all?

FAS should be foliar applied and allowed to be absorbed by the plant for 4 hours prior to watering in to get the best effect. I use FAS all the time along with a scoop of CA to drive pH down prior to mixing the iron in and haven't had any issues as long as you follow the recipe.

San

· #837 · 12 mo ago

A scoop of CA also won't turn your water into a strong acid, your rain is likely more/just as acidic as your FAS solution.

TampaBayFL

· #838 · 12 mo ago

TampaBayFL said:
I did something similar last week. I wimped out and used 2 gallons of hot water and 4 oz FS and ~4 oz AMS, plus 1/4 tsp of CA. The water stayed light green even though my starting pH was off the charts (something in the 8's). After the 1/4 tsp of CA is was too low of a pH for me to measure (below 6).

I sprayed this on some test areas and even a few days later there is no discernible color difference on Citra Blue or Bermuda. I sprayed one area in particular HEAVY and I could see some slight damage but nothing horrible.

I gave another area another test with FAS. I used ~6 oz of FS and ~5 oz of AMS (with a small amount of CA to keep the water acidic and such that the mix stayed light green) for ~1500 ft area.

Most of this I used on a Bermuda area and a small amount on the Citra Blue. I purposely applied the FAS rather heavy on some of the Citra Blue to really push it to see if I could visually tell a difference.

I took a photo of a couple of representative blades.......,one treated heavily with FAS to the point of damage and the other untouched. There is a discernible difference when a photo is taken, but it's hard to see where I started and stopped the test in the yard in reality.

The Bermuda I did appears noticeably bluer in color.

See less See more

TampaBayFL

· #839 · 12 mo ago

Here's another photo of the same two grass blades, now I can't tell which is which, lol

See less See more

TampaBayFL

· #840 · 12 mo ago

Since my tests with FAS did not result in any discernible visual change...... Is it possible the grass blades are simply "iron saturated"? I assume something along these lines is going on as my recent soil tests from three different spots in the yard all show that the iron levels were very high already (8-9 lb/1k sq ft).

821 - 840 of 876 Posts