Phosphates & Soil

Phosphates, how certain types of soils can make it UNAVAILABLE to your crop

Phosphates can be your most expensive nutrient per pound most years and this year is no exception.  It is well documented and known that in a lot of cases in Saskatchewan, what you are spending your money on may not be available to this years, or subsequent years, crops?

Many factors affect the breakdown and availability of phosphates.  Here are some:

  • Soil texture. Soils high in clay content fix/absorb more phosphorus than those with less clay.
  • Soil temperature. Low soil temperature will reduce P availability by slowing the movement of phosphorus from the soil to the root and reducing mineralization of organic matter to plant available inorganic phosphorus.
  • pH of the soil. Phosphates work best in soil pH’s of 6.0-7.5.  Such a precise requirement represents a real challenge to agriculture in Saskatchewan as most of our soils have pH well above 7.


  • CEC (Cation Exchange Capacity). The higher the CEC the more capacity the soil can hold cations that can tie up phosphates and make them unable for the plant to get.
  • Base Saturation %. The number of positive ions that will tie up the negatively charged phosphate element.
  • Plant root type. Plants with more fibrous roots, compared to tap roots, explore more soil volume in the 0 to 6 inch depth where phosphorus is prevalent.  Therefore, fibrous roots are better able to recover phosphorus.
  • Type of phosphate being used (Monoammonium, Diammonium, Orthophosphate, etc). Phosphates need to break down into other forms of phosphate to eventually be able for the plant to be able to “drink”.

In soils with a pH of 7.5 or higher, 60-70% of phosphate being put in the ground can be tied up by the soil and unavailable for the crop you are trying to feed.

There are products out there to help make your phosphate more available and your dollar more efficient.  New and more complex phosphate products or treatments for our existing products.

Here at SynergyAG we are working hard to learn more about these new products and companies to make sure that what is coming down the pipeline is going to be effective and profitable for our customers.  Please look up your nearest SynergyAG location and get the information you need to help you get the right products for your farming application and get the actual bang for your dollar.

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