Composition and qualities

What is Polyhalite?

Polyhalite is a naturally occurring mineral that contains four key elements beneficial to plants: potassium, magnesium, calcium, and sulfur. These nutrients are crucial for healthy plant growth and development.

There are two different ways to express the proportions of different nutrients in polyhalite. The first is the component weight method, which tells you if you had 100 kilograms of polyhalite, how many kilograms of potassium it contains, how many kilograms of magnesium, calcium, sulfate ions, etc. That is pretty straightforward.

The second is the oxide equivalent figure, which gives the weight of each of a number of conventional oxides that would be obtained from a conventional assay procedure carried out on 100 kilograms of the fertilizer.

These two ways to express the proportions are explained on the page Component Weights and Oxide Equivalents. Here, we will just present the percentages in two tables as follows.

Component weights:

Potassium (K): 12.97% 

Calcium (Ca): 13.30% 

Magnesium (Mg): 4.03% 

Sulfate (SO4): 63.75% 

Water (H2O): 5.98%

Oxide equivalents:

K2O equivalent: 15.6% 

CaO equivalent: 18.6%

MgO equivalent: 6.7%

SO3 equivalent: 53.0%

H2O equivalent: 6.0%

• Potassium is vital for regulating plant functions, contributing to the strength and quality of crops.

• Magnesium plays a central role in photosynthesis, essential for energy production in plants.

• Calcium strengthens plant cell walls, giving structure and resilience.

• Sulfur is important for protein synthesis and enzyme function in plants.

Soil Health and Polyhalite

One of the less talked about, but equally important aspects of polyhalite, is its impact on soil health, particularly in soil structure and microbiota. Healthy soil is the foundation of successful farming, and polyhalite contributes positively in several ways:

• Enhancing Soil Structure: Calcium in polyhalite helps improve soil structure. Better soil structure means better water retention and drainage, making it easier for plants to access nutrients.

• Beneficial for Soil Microbiota: Soil is teeming with life – microorganisms that play a key role in nutrient cycling. Polyhalite's balanced nutrient composition supports a healthy soil ecosystem. For example, in polyhalite, the potassium, calcium and magnesium are balanced with sulfur, not chloride. Sulfur is required by all organisms as it is essential to many proteins. Chloride is needed by microbiota only in trace amounts, meaning that the high chloride content of fertilizers like potash are unnecessary and potentially harmful, while all the main ingredients in polyhalite are essential macronutrients.

It is interesting to note that chloride is actually a nutrient in small amounts. Which is another reason why polyhalite is beneficial for crops. There's nearly always a little bit of chloride (up to 4% or so) that naturally occurs in polyhalite rock. That percentage is enough for healthy plants.

The Sustainable Choice

The gradual-release nature of polyhalite aligns perfectly with the natural growth cycle of plants, providing a steady supply of nutrients. This gradual nourishment means fewer applications, saving time and resources, and reducing environmental impact. There is also the fact that polyhalite is nothing more than the natural rock ground up. That means less waste, no byproducts, less processing, and a lower carbon footprint in its production process.

My Ongoing Journey

I’m still exploring all the facets of polyhalite. It’s a journey that began with a vision, but has grounded me in a very real and promising aspect of agriculture. I invite you to join me in learning more about how polyhalite can revolutionize our approach to farming – for the health of our plants, our soil, and our planet.

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