Farming Video | Why Kelly Garrett Uses Sulfur as a Soil Amendment, Not Just Fertility

16 Dec 25

Kelly Garrett’s not pulling punches in this one—he says base saturation ought to be Agronomy 101. But the truth is, a lot of folks still aren't paying close enough attention to it. In this clip, Kelly breaks down a real-world example from a farmer in Missouri who used heavy ammonium sulfate to correct a soil imbalance—and saw a big difference in his corn. But here’s the twist: it wasn’t about feeding the crop. It was about unlocking nutrients already there. Kelly explains why he sees sulfur as a soil amendment, not just fertility, and how it can free up tied-up phosphorus and potassium if your base saturation's out of whack. If you’re scratching your head at your soil test this winter, this is worth a watch.

00:00 Base saturation, in my opinion, should be agronomy 1 0 1 for a farmer or an agronomist. 00:00:08 And I don't believe that is, and that is a little alarming to me. So this winter, as you're studying your soil test 00:00:15 and looking at your 26 crop, I would encourage you to become more educated on what base saturation means on your farm if you're not, 00:00:24 if it isn't something you're proficient at. I'm specifically referring to a conversation on X that I was involved in with my friend Gavin Spore, Missouri. 00:00:33 Gavin, uh, Gavin posted, uh, a thank you to me and said that, uh, he appreciated my suggestion of using a heavy rate of ammonium sulfate on, on some 00:00:45 of his acres, uh, and, and how good the corn looked all year. And I, I don't specifically remember 00:00:51 what Gavin's base saturation was, but he, he had some trouble. I don't remember if the mag or the cow was high, 00:00:58 but what it was, and it was tying up the phosphate and, uh, it was also limiting the availability of the potassium. 00:01:05 The ammonium sulfate unlocked both of those. And, uh, just to make sure everybody understood, when I responded to Gavin 00:01:12 and told him I appreciated the kind words, I said, everyone needs to understand that we're not looking at the sulfur in the ammonium sulfate application as fertility. 00:01:21 It was a soil amendment and if somebody pushed back because they didn't understand that, and, and so I'd like to explain obviously, sulfur's fertility, 00:01:30 but in this case that that sulfur to me is a soil amendment. When the hydrogen atom breaks apart the calcium phosphate 00:01:39 bond or the magnesium phosphate bond, the sulfur becomes the most attractive thing to the calcium or magnesium, depending on what your problem is. 00:01:46 And it's because of the molecular way to the sulfur. Um, the cal of the mag will be attracted to it relative to the phosphate. 00:01:54 So if we put out a heavy dose of ammonium sulfate and by def to define heavy, it could be two, three, or even 400 pounds. 00:02:03 It depends on how far out of balance or off your base saturation is. It will very much amend the soil. 00:02:09 Um, I've seen soils before where the, the Kinsey lab has said it would take a thousand pounds of sulfur to get that soil back to a perfect state. 00:02:20 So please don't think three or 400 pounds of ammonium sulfate. While it sounds like a lot, it's really not 400 pounds 00:02:27 of ammonium sulfate. It equates to 92 pounds of sulfate going into the soil, again, relative to a potential needed of a thousand. 00:02:35 It's not a lot, but it will make a big difference in your soil. You will see an economic return, 00:02:40 which is truly what we're after. It will really help solve your problem. And so the reason that I say that, that sulfur is not viewed 00:02:48 as fertility is because when it combines with the mag or the cow, I don't know that any of that sulfur, I sure would not figure on it ever being available 00:02:58 to the plant because it's tied up the way the phosphate will. You're putting that sulfur out there to be held hostage 00:03:04 by the mag of the cow and to allow the phosphate to become available. And so when you do this, um, depending on 00:03:11 how bad your phosphate problem is, you potentially don't need to put out any phos. It's in your soil. It's locked up into a savings account, 00:03:19 and now it's being released. So again, the reason that I say the sulfur's not fertility is because it's replacing the phosphorus in that compound in 00:03:29 that molecule, and it will become unavailable later on in the season. You potentially need to address your sulfur needs 00:03:36 with a foliar application. That is why I say the sulfur is not viewed as fertility. 00:03:42.075 --> 00:03:43.725