You guys know that I am not an extremist who hates anything and everything If you are buying “off-the-shelf” lawn fertilizers that come in a 4 or 5 step ‘system’ then chances are you are getting ammonium sulfate as your primary nitrogen source. Ammonium nitrate, ammonium sulfate (sulphate) and urea are all very common forms of quick release or immediate release nitrogen 
fertilizers. They are quick release because the N becomes available for plant use (in this case turf) as soon as water dissolves it. This is why you are told to “water in” your fertilizer… But are they good or bad and is there a better way to get a nice green nitrogen enriched lawn?
Positive Results From Using Ammonium Sulfate On Your Lawn
Ammonium sulfate (NH4)2SO4 provides the very best and fastest greenup possible from a synthetic blend fertilizer. I’ve used them all (urea, sulfur coated urea, ammonium nitrate) and none can perform as well. The nitrogen is immediately available for plant use once water contacts it and it absorbs into soils well with little loss due to evaporation. All of this assumes application rates in accordance with labeling of course.
in addition, Ammonium Sulfate tends to provide a much longer sustained blue-green color in Kentucky Bluegrass, Perennial Rye and Turf Type Tall Fescue, mimicking the effects of chelated iron in many cases.
Down and dirty – if you are going to use a high nitrogen synthetic fertilizer for a fast green or to make your lawn grow, get one that contains ammonium sulfate, it’s very affordable and works wonders – literally. Just don’t get in the habit of slogging this stuff on your lawn every 5 weeks until winter! There are better ways…
Negative Results From Using Ammonium Sulfate On Your Lawn
I want you to remember back to when you were a kid and how much you enjoyed getting a sugar rush from eating a bunch of Halloween candy. It was great to suck down Reeses, MilkyWay bars and a bunch of other sugary goodies… until about an hour later when you CRASHED big time! You went from buzzing like a bee, to lethargic and sleepy like a sloth. THAT my friends is what can and will happen when you use ammonium sulfate fertilizers on your lawn.
The AS fertilizer pushes top growth in the lawn… to mega proportions. That looks good at first, but the underlying problem is that the turf root system isn’t stimulated in the same way and it oftentimes too thin and weak to support all that extra top growth. Eventually you end up with a major imbalance that causes the turf to actually thin out and become susceptible to disease.
The only way to keep up the burst of growth and color created by the ammonium sulfate is to add more about every 5 or 6 weeks. Over time, the salts in this compound will ruin your soil.
Am I 100% Against Ammonium Sulfate?
No, as I said, i am not an extremist. There are times when it’s a good idea to “kick start” your grass to get it growing or moving. The key is to balance things out and work on your soil’s overall health in the meantime.
If you are going to use a synthetic fert on your lawn, I almost always recommend applying Milorganite or Ringer at the exact same time! Yep, same time (or soon after anyway – within 24 hours)… don’t worry, the Milorganite or Ringer will not burn the lawn (the synthetics will if you apply them outside of label instructions however).
The reason we apply some organics at the same time as the synthetics is to counter-balance soil biotic activity. I want you to stimulate the soil activity with the organics so that roots structure can catch up to the top growth your synthetic fert is creating. It’s a process, and of course, isn’t going to end up perfect over night, but it’s something that can be balanced out if you will be patient.
If you need more specifics, or want to learn a true, sustainable and responsible way of caring for your lawn, get my ebook here and learn it all!
