This spring, we will be switching our colloidal soft rock phosphate from the Calphos brand to Fertoz (fur-toes errr… furt-oz) brand. While we might not know how to pronounce the name, we do know that your plants will love it.

Plants create sugar from sunlight through photosynthesis, but there are nutrients they need to thrive that they cannot make themselves. The big three are nitrogen (N), phosphorous (P), and potassium (K). Plants need all three of these nutrients to develop and phosphorous is especially important for root, stem, flower, and fruit development. Colloidal soft rock phosphate is a natural source of phosphorous for your garden.

Green seedlings recently sprouted from the dirt
Photo by Francesco Gallarotti on Unsplash

What is Calphos??

If you are wondering what colloidal soft rock phosphate is, here is a breakdown:

Colloidal – a mixture of molecules where one is evenly distributed throughout the other

Soft Rock – a sedimentary rock

Phosphate – a molecule made of one phosphorus atom and four oxygen atoms

The Calphos brand phosphate was mined for years in Florida. Unfortunately, the deposit has been depleted, and Calphos phosphate is no longer available. The new brand, Fertoz, is mined in Montana and has many benefits.

One benefit is that Montana is closer to Washington than Florida is! This means less fossil fuel is used to get it from the mine to your garden.

Another benefit is that Fertoz has more available phosphate. Plants are only able to take up phosphorous when it is in the right form. Available phosphate refers to the amount that your tomatoes and dahlias can actually use. Calphos has 3% available phosphate while Fertoz has 7%, which means your plants are getting more of the nutrients they need to produce an exquisite harvest.

Fertoz dark grey granular in a metal scoop         Fertoz light tan granulars in metal scoop

(Photo by Darrow Brooks)

{Fertoz is dark grey colored granular & Calphos is a light tan colored granular}

Colloidal soft rock phosphate is mined which means it contains heavy metals. A ‘heavy metal’ is a toxic metal element even at low concentrations, think mercury (Hg) and lead (Pb). Soils around the world have natural concentrations of heavy metals in them. When being sold, mined products must meet concentration requirements that do not exceed the area’s natural background levels. Fertoz goes above and beyond by testing their phosphate about twelve times more often than is required, and the results indicate lower heavy metal levels.

You can learn more about plants and phosphorous from Iowa State University.

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