Polysulphate: Secondary Macronutrients Matter to the Bottom Line

As an agronomist, I often ask what farmers want when selecting fertilizers to manage their crops and what crops and soils need to thrive. For most of us, cost is a significant consideration in these volatile markets, alongside other factors like local availability, convenience, proven agronomic performance, and environmental impact. When I drill into it, the 4R framework for nutrient stewardship continues to be emphasized. Why? Because considering the right source, right rate, right time, and right place optimize yield and profitability while taking the right steps for environmental stewardship. Maybe this is why I get excited when we find simple, natural solutions that can solve more than one nutrient management challenge.  

Nutrient Stewardship 

While 4R nutrient stewardship is often associated with nutrients like nitrogen and phosphorus, the fact is that the 4R approach can be applied to potassium (K) and the secondary macronutrients – calcium (Ca), sulfur (S), and magnesium (Mg). We might use some nutrients in smaller quantities, but every nutrient plays a vital role in our fields. With increasing demands placed on growers, finding products that can simplify processes and reduce costs without sacrificing the environment is crucial to our survival.  

When we look at what we put into the soil, not just what we get out of it, we recognize that this is a balancing act. We must work with nature to use our resources as effectively and efficiently as possible, from our machinery and workforce to our soil microbes and water resources. Using fertilizer products that simplify processes, reduce applications, and safeguard against environmental challenges while maximizing yield is the future of ag. 

Natural Multi-Nutrient Solutions 

Today, there are an abundance of nutrient management solutions, products, and protocols available to growers. And while some innovations are new technological developments, others are simply discoveries of already existing natural resources. Polysulphate, for example, is a naturally occurring mineral fertilizer mined exclusively by ICL. Deposited in the earth 260 million years ago, each Polysulphate granule contains sulfur, potassium, calcium and magnesium – four of the six essential macro-nutrients required for optimal plant growth. Today, ICL mines Polysulphate from one location in the world, approximately 1100 to 1400 meters deep underneath the North Sea along the coast of the United Kingdom.  

It provides a convenient 4-in-1 low salt index source of low-chloride K, Ca, S, and Mg with a sustained release nutrient profile. This means it is not only seed-safe, but its nutrient release aligns to meet plant demand, and its flexible application profile allows for integration into any nutrient management program. It is applicable to diverse crops, including small grains, pulses, potatoes, forages, and specialty crops, and as a natural mineral, it is just as nature intended.  

Why Focus on Sulfur? 

Studies suggest that while sulfur is paid less attention than primary macros, it is one of the most limiting nutrients on the Canadian Prairies. It also plays an important role in both yield and quality. Since the sulfur in Polysulphate is in sulfate form, it provides immediate plant availability once released from the granule. But what makes Polysulphate really unique compared to other sulfate-S fertilizers is that the sulfur is gradually released throughout the entire season. This season-long release ensures that excess sulfate is not present in the soil where it can be susceptible to leaching, while also ensuring sulfur is released precisely when the crop needs it.  

While Polysulphate contains only one-fourth of the potassium of potash (potassium chloride), the potassium is very low chloride (about 2.4%). Its low salt index also makes it ideal for sensitive seeds like canola. As a bonus, it naturally contains plant-available calcium that, unlike gypsum, begins to release sooner in the season, coinciding with the time that crops, like potatoes, need calcium.  

The Bottom Line  

Focusing on comprehensive nutrient management can help boost both yield and quality. We can grow more, higher-quality crops with less and continue to act as stewards of our lands, by integrating multi-nutrient products that align crop demand, superior seed safety, and excellent blending characteristics.   When considering your fertilizer program, think about multi-nutrient products, like Polysulphate. Your local agronomist can help you find what works for you!