Phosphorus fertilizer provides on-demand buffet for plants

Posted in: Fertility

Phosphorus is an essential part of every plant’s diet. Yet it’s lack of mobility in the soil, and challenges getting it to the roots when they need it the most can leave plants hungering for more: especially in soils that fall outside of the neutral pH range.

A new category of agricultural fertilizer is making Phosphorus application more practical and efficient than ever in high and low pH soils – using an innovative formulation composed almost entirely of struvite (magnesium ammonium phosphate hexa-hydrate). Since it is not water soluble, this fertilizer has the distinct advantage of remaining in the soil until the plant demands it. Not only that, the phosphorus is not prone to tie up, which is common in high and low pH soils.

Ostara Nutrient Recovery Technologies has received registration for Canada’s first struvite fertilizer, sold under the trade name, Crystal Green®. Crystal Green® is now available at select farm retail outlets and can provide a steady source of Phosphorus for all crops.

Backed by extensive research.

Ongoing research shows that replacing 25% of MAP or DAP with a struvite fertilizer can significantly increase the amount of on-demand, plant-available Phosphorus throughout the following growing season.

This has been supported by a newly released study by North Dakota State University. Cereals extension agronomist, Joel Ransom, conducted rate of release trials after harvest over an eight-month period, from October 1st to July 2018. Hundreds of sample bags with MAP, DAP and Crystal Green® were buried at five depths in a neutral pH.

Across all depths, only 5% to 18% of the MAP was recovered, while 94% to 98% of the Crystal Green (struvite) was recovered.

These results support the argument for incorporating struvite into a MAP or DAP application for a season-long source of plant available Phosphorus.

How a struvite fertilizer complements MAP or DAP.

Where MAP and DAP, are water-soluble – struvite is root activated (citrate soluble). Citrates are organic acids released by a plant through its roots when it requires Phosphorus. Since struvite is virtually insoluble in water, it can remain available in the soil for long periods – until the plant requests it.

Blending water soluble MAP or DAP with this citrate soluble struvite as part of a fall application provides a key advantage.

Because it is water soluble, MAP or DAP will release plant-available Phosphorus at the earliest growth stages – triggered by early season moisture and precipitation. This is critical since Phosphorus plays a central role in root development. (Learn more about crop available phosphorus)

Once the roots develop and are able to exude citrates, the Phosphorus reserves in the struvite become available – and are shown to last well into the growing season.

Canola, cereal and pulse crops are all known to release citric acid in strong concentrations, and all respond very well to this fertilizer (VIEW TRIAL DATA).

How struvite prevents Phosphorus tie up in high and low pH soils.

It is estimated that nearly two-thirds of farmland on the Canadian prairies falls outside of the neutral pH category.

One of the knocks against MAP and DAP is that neither provide a steady and lasting source of Phosphorous throughout the growing season. Especially in high pH (basic) soils where it has a tendency to get tied up with Calcium; and in low pH (acidic) soils where it can tie up with Iron or Aluminum.

The unique formulation of struvite gets around this challenge because the phosphorus is already bound to Magnesium. This prevents it from getting tied up in the soil with Ca, Fe or Al. The tie to Magnesium is readily broken once the citrates are released.

Improved Seed Safety.

On top of this, struvite has a significantly lower salt index than MAP or DAP. A struvite fertilizer like Crystal Green® has a salt index 70-75% lower than these products. This represents the lowest salt index of any Phosphorus fertilizer.

Fall Application Opportunities.

While this new struvite fertilizer is a fit for all crops, and will be most widely used as a spring-applied fertilizer (as part of a MAP or DAP application), it will be of interest to those seeding winter wheat and fall rye – due to its ability to remain available in the soil over winter and well into the next growing season.

In winter wheat trials conducted at Kansas State University, a 100% MAP application resulted in a yield of 30.6 bu/ac. By replacing 15% of MAP with Crystal Green®, yield jumped to 34 bu/ac, and increased to 34.5 bu/ac at 25% inclusion.

Results in spring wheat and canola are equally impressive.

An “all you can eat” source of Phosphorus.

There has long been an appetite for a safer, more efficient Phosphorus fertilizer, especially in low and high pH soils. Struvite fertilizers are poised to satisfy that hunger.

MAP DAP Crystal Green
90% Water Soluble 93% Water Soluble 4% Water Soluble
10% Citrate soluble 7% Citrate Soluble 96% Citrate Soluble
27 Salt Index 29 Salt Index 7.7 Salt Index


The science behind Crystal Green® as an agricultural fertilizer has been in development for more than a decade.

Taurus would like to share the compiled research highlights on this innovative new product with you.

Download the research highlights on Crystal Green

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