All crops need sulphur — that’s a given. But since nitrogen is the main driver of most fertility programs, sulphur often gets overlooked in the planning process.
That needs to change, says Mitch Poiron, marketing representative for Nutrien. “I think there’s a situation where some growers are too familiar or comfortable with their existing fertility program,” he says. “The problem with that is when growers are driving for more yield, they need to review all fertilizer rates.”
One of the few times sulphur is front and centre is when canola is in rotation because it’s known to contribute significantly to yield. “We’ve been fertilizing canola with sulphur since the beginning,” says Poiron. “Canola is a crop where a grower can easily see a response to sulphur application. But when we deal with cereals, corn, flax, soybeans and pulses, it is often overlooked.”
For the longest time, says Poiron, Mother Nature was able to keep up with sulphur demand. But decades of increasing yields have meant higher sulphur removal, and that combined with low sulphur application rates have left many prairie soils depleted.
So what’s a farmer to do? It comes down to having a good plan, a good product and a good understanding that rebuilding sulphur levels in your soil might take some time, but the rewards will be worth it.
The importance of soil type
As you know already, there are two sources of sulphur: sulphate, which is immediately plant-available, but prone to early leaching, and elemental sulphur, which is not immediately plant-available, so it needs time and the right conditions to be oxidized into a useable form.
That oxidization process is aided or thwarted by any number of things, including soil type and condition, and healthy microbial activity.
“Historically, if you look at areas that produce really good crops then you’re likely looking at areas with higher sulphur depletion,” says Poiron. For instance, in the region of south-central Manitoba where he works, high-producing areas are also typically on lighter textured soils under irrigation, which can compound leaching.
“Using multiple sources of sulphur can help replenish the soil profile where leaching has occurred to help maintain maximum yield potential,” he says. But any soil type, anywhere that has been producing higher yields over time is at risk of sulphur depletion — it’s basic math. “Crop removal exceeds what’s being put down.”
Other factors to consider are topography — rolling land can have wildly different sulphur levels on knolls compared to depressions — and soil microbial levels, since bacteria and fungi are essential to breaking down elemental sulphur into an available form.
The challenge for farmers is ensuring that none of these things get in the way of nice, even sulphur availability throughout the season, from seeding to harvest, without having to worry about a big rainfall leaching it away, or that sulphur is locked down in the subsoil where plants can’t get at it.
And this is where Poiron is keen to talk about a new tool that can make sulphur delivery easier and more reliable — Smart Nutrition™ MAP+MST®.
Thinking differently about sulphur delivery
Simply put, Smart Nutrition MAP+MST is a granular fertilizer that delivers sulphur and phosphate to your crops in a more efficient and consistent way.
So what does that mean? Nutrien uses a patented process, used under license from Sulvaris Inc., called Micronized Sulphur Technology (MST) to micronize elemental sulphur to an average particle size of 15 microns. That teeny tiny size is important because the smaller these particles are, the more surface area there is for soil microbes to act on and turn the elemental into the available form.
MST is integrated into the mono-ammonium phosphate (MAP) manufacturing process and the result is consistent percentages of phosphate and sulphur from granule to granule, and very high nutrient density.
“You know you’re going to be putting down phosphate and sulphur anyway, and this product simplifies that process and is easier to apply,” says Poiron. Part of that ease comes from the product’s very low salt index so it can be safely placed with seed in a spring application.
It is, in essence, a slow-release fertilizer that provides crop-available sulphur throughout the season without leaching away. For farmers on heavier soils, Smart Nutrition MAP+MST can be applied in the fall. Winter soil temperatures will hold it in a kind of stasis and the slow release starts in the spring when soils warm up.
To Poiron, Smart Nutrition MAP+MST is coming at just the right time because the issue of sulphur depletion is recognized among growers, but correcting the problem isn’t always straightforward. Soil testing for sulphate, for instance, is notoriously unreliable, so how does a farmer reasonably figure out where it’s needed and how much?
“This product, in general, addresses a lot of those concerns,” says Poiron. “The high nutrient density means covering more acres per tonne of product, and the homogenous nutrient distribution means Smart Nutrition MAP+MST delivers balanced nutrition, it’s easy to apply and you can go and focus on other tasks.”
Have a plan
Poiron is quick to point out that Smart Nutrition MAP+MST isn’t a “set it and forget it” type of product. On the contrary, he says it can be an important part of your fertility plan, but having an overall plan is essential.
“Our product is a great tool in the toolbox, but it needs to be discussed with your retailer or agronomist, you need to figure out how it fits on your farm, and you need to be thinking long term.”
For instance, in cases of highly sulphur-depleted soils, or where there has been no historical use of elemental sulphur on a farm, sulphur depletion is not something you can solve in a season, so you need a multi-pronged approach.
In situations like that, Poiron recommends growers use Smart Nutrition MAP+MST with ammonium sulphate in the first two years. “It’s important to give soils time to build microbial activity,” he says. “The ammonium sulphate will help ensure sulphur is available short-term and give time for the Smart Nutrition MAP+MST to oxidize.”
It’s a program of rebuilding and replenishing, he says. “You might have a bumper crop one year and that will remove a lot of sulphur. Or you might have a huge rain event that leaches it away. You need a new fertility plan that aims for bumper crop potential, but limits environmental affects.
“It’s a philosophy approach,” says Poiron. “It’s an investment in your crop and soils.”