RealAg Radio Product Spotlight: Dr. Robert Mullen Explains Forms of Sulfur Fertilizer

Dr. Robert Mullen, Director of Agronomy at Nutrien, discusses Smart Nutrition™ MAP+MST® and how it’s different from other traditional forms of sulfur with RealAg Radio. Listen to the interview below or read Dr. Mullen’s answers below.

Talk about Smart Nutrition MAP+MST and how it’s different than some of the other more traditional forms of sulfur.

So there’s a couple different products that are available out there on the market. The most traditional would be the ammonium sulfate, that’s actually a product we manufacture and sell as Nutrien, very commonly used as a sulfate source. And then there’s elemental sources of sulfur. The primary difference between the two is if you’re talking AMS, that’s in a salt sulfate form, it’s immediately available the day it hits the ground. The only challenge we have with AMS is if you’re applying that in the seed row, it is a fairly salty fertilizer material so it can contribute to some seed injury. Elemental sulfur, it’s not a salt contributor, it’s just straight sulfur. The problem with this material is it’s not readily available—it actually has to be oxidized and put into a sulfate form for a plant to actually use it. The traditional challenge with elemental sulfur products is the particle size, they do oxidize but they can oxidize relatively slowly and some of that, and a large extent of that, can be controlled by the particle size and that’s what we’ve done with the Smart Nutrition MAP+MST product that we market at Nutrien. It’s a very small particle size, so we’re going to be able to oxidize that material relatively rapidly. So, that’s the real difference between MAP+MST and the traditional products that exist in that sulfur space.

What are some of the key benefits from a crop production standpoint?

The biggest thing, and we really market this for Western Canada, is the fit within that seed row application of fertilizer material. With the MAP+MST, we’re able to put that in row with the seed. The other aspect of this product that makes it beneficial is the nutrient density. We’ve got nitrogen, we’ve got phosphorus, we’ve got sulfur at relatively high concentrations and that can make it a little bit more efficient with regard to use with application rates that can be achieved. Those are the two primary things that we promote with regard to how this product really impacts the production operation for the farmer.

How does Smart Nutrition MAP+MST compare to traditional MAP, especially in terms of seed safety?

So I mentioned this a couple times already, and the biggest difference is we’re able to get that MAP with some sulfur into that seed row, it’s going to have a lower salt index than a traditional MAP. So, from a seed safety perspective, you can feel pretty confident that I can put this product in the seed row, and it shouldn’t present any issues with regard to stand or seed emergence.

Whether it’s Eastern Canada or Western Canada, have you done any trials in this country on seed safety?

As you can probably imagine, we’ve been pretty busy the last couple of years, we have a couple of really good cooperators that we work with specifically on this issue. Looking at: can we push rates of application? Just seeing: is our product able to be safely applied in row and not have any emergence issues? This past year, which shouldn’t be much of a surprise considering the dry conditions that were experienced, our product did perform better than a MAP+AMS, specifically at those higher rates. Actually, it was across all rates but you really started to see the difference when you were really pushing that phosphorus rate.

What crops are you seeing the best results in from Smart Nutrition MAP+MST?

Probably shouldn’t be surprised when you’re talking about a sulfur-containing fertilizer product in Western Canada, we’re probably going to be focused on canola, and that turns out to be the case. So that’s really where we’ve been focused. We have done some work on spring wheat as well. Talking about small grains in Western Canada, not traditionally a crop that’s been fertilized actively with sulfur. We sort of think about it in the rotation if there’s some sulfur leftover from that canola that will be able to take it up. But, again, for us on the research side, it’s important that we test as many different crops in as many different environments as we possibly can.

What about corn and soybeans?

We actually don’t have active field research in Western Canada on corn and soybeans. As you can probably guess, this is a product we do market south of the border here in the States, so we have been doing corn and soybean field research all the way from North Dakota down to Georgia. So, we have been covering the gambit of crops and again, evaluating different environments, different application methodologies to make certain we’re positioning this product for success when we’re giving farmers recommendations with regard to how to use the material.

Can Smart Nutrition MAP+MST be applied in the seed row?

Absolutely, that’s really where we’ve been focused in Western Canada because that’s a traditional practice, right. Traditionally, it’s been a combination of MAP+AMS to get your phosphorus needs for that crop and then you’re going to throw in a little bit of sulfur. Specifically early, specifically for canola, its uptake pattern, it really has a thirst for sulfur early in that growing season. So, that’s how we’ve been positioning this product as more of a seed row application. We actually had some field research this past year comparing MAP+AMS at equivalent rates on the phosphorus side. When we compare that MAP+AMS to a MAP+MST in the seed row, we had at least one experiment this past year where we had a better stand result where we were supplying that MAP+MST. That MAP+AMS, I’m not saying it’s a bad combination or it’s a bad product, but you do run the risk, specifically if you’re pushing rates of having some seed injury and decreasing your germination rate.


For more information about Smart Nutrition MAP+MST, please contact your local rep.