We are independent & ad-supported. We may earn a commission for purchases made through our links.

Advertiser Disclosure

Our website is an independent, advertising-supported platform. We provide our content free of charge to our readers, and to keep it that way, we rely on revenue generated through advertisements and affiliate partnerships. This means that when you click on certain links on our site and make a purchase, we may earn a commission. Learn more.

How We Make Money

We sustain our operations through affiliate commissions and advertising. If you click on an affiliate link and make a purchase, we may receive a commission from the merchant at no additional cost to you. We also display advertisements on our website, which help generate revenue to support our work and keep our content free for readers. Our editorial team operates independently from our advertising and affiliate partnerships to ensure that our content remains unbiased and focused on providing you with the best information and recommendations based on thorough research and honest evaluations. To remain transparent, we’ve provided a list of our current affiliate partners here.

What is Phosphate Fertilizer?

By Christian Petersen
Updated May 16, 2024
Our promise to you
HomeQuestionsAnswered is dedicated to creating trustworthy, high-quality content that always prioritizes transparency, integrity, and inclusivity above all else. Our ensure that our content creation and review process includes rigorous fact-checking, evidence-based, and continual updates to ensure accuracy and reliability.

Our Promise to you

Founded in 2002, our company has been a trusted resource for readers seeking informative and engaging content. Our dedication to quality remains unwavering—and will never change. We follow a strict editorial policy, ensuring that our content is authored by highly qualified professionals and edited by subject matter experts. This guarantees that everything we publish is objective, accurate, and trustworthy.

Over the years, we've refined our approach to cover a wide range of topics, providing readers with reliable and practical advice to enhance their knowledge and skills. That's why millions of readers turn to us each year. Join us in celebrating the joy of learning, guided by standards you can trust.

Editorial Standards

At HomeQuestionsAnswered, we are committed to creating content that you can trust. Our editorial process is designed to ensure that every piece of content we publish is accurate, reliable, and informative.

Our team of experienced writers and editors follows a strict set of guidelines to ensure the highest quality content. We conduct thorough research, fact-check all information, and rely on credible sources to back up our claims. Our content is reviewed by subject matter experts to ensure accuracy and clarity.

We believe in transparency and maintain editorial independence from our advertisers. Our team does not receive direct compensation from advertisers, allowing us to create unbiased content that prioritizes your interests.

Phosphate fertilizer is a fertilizer that is high in phosphorous. Most phosphate fertilizer comes from phosphate rock, a mineral mined in massive quantities of millions of tons from locations around the world. This mineral provides one of the three main nutrients needed by all plants for vigorous growth; the other two are nitrogen and potassium.

Phosphate rock is most often mined in large open pit mines; notable deposits are in Morocco, China, Florida and South America. This raw ore is occasionally used as a fertilizer without any further processing, especially in acid soils, where it serves the dual purpose of raising pH. Rock phosphate fertilizers are becoming less common, as the raw rock provides relatively little phosphorous for its weight and transportation costs make it more expensive than refined phosphate fertilizer.

The process by which phosphate rock is converted to phosphate fertilizer involves treatment with sulfuric acid; the result is often called "super phosphate." This treatment with sulfuric acid draws the phosphates from the raw ore and creates a water soluble form. This is mixed with water to create a number of similar fertilizer compounds in a concentrated liquid form which is easy to apply to fields and crops.

The water soluble super phosphate fertilizer is sometimes packaged and shipped in granular form to reduce shipping costs. This type of phosphate fertilizer is then mixed with water by the end user for application. Phosphate fertilizers are sometimes combined with other primary fertilizers to create complete fertilizers. Potassium phosphate and ammonium phosphate are phosphates combined with potassium and ammonia, respectively.

Complete fertilizers contain amounts of all three of the primary plant nutrients; these are commonly combined into a granular mix as well and packaged for shipping. These fertilizers are labeled according to the relative percentages of the amounts of the three ingredients in the mix by weight, and these proportions will be denoted on the label by a series of three numbers separated by dashes. These numbers refer to the amounts of nitrogen, phosphorous and potassium respectively and are generally represented by their individual chemical symbols N,P and K.

A complete fertilizer may be labeled as having a formula of 10-15-20 N-P-K. This means that the fertilizer has 10% nitrogen by weight, 15% phosphorous by weight, and 20% potassium by weight. The rest of the product is made up of other ingredients, which may include other nutrients plants used in lesser amounts like sulfur, iron, magnesium and others.

HomeQuestionsAnswered is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.

Discussion Comments

By anon140118 — On Jan 06, 2011

The NPK explanation is incorrect. 10-15-20 is 10 percent N but the P and K values are based on P2O5 and K2O. P is 43 percent of P2O5 and the amount of elemental P is 15 x 43 percent = 6.5. The conversion for K is 0.86 x 20 = 16.6 percent. It would be far more sensible if the NPK straightforwardly expressed the elemental percentages directly - as is the case for N.

HomeQuestionsAnswered, in your inbox

Our latest articles, guides, and more, delivered daily.

HomeQuestionsAnswered, in your inbox

Our latest articles, guides, and more, delivered daily.