A pH test. Crude phosphate fertilizer can be used to increase soil pH.
Phosphate fertilizer is a phosphorus-rich fertilizer. Most phosphate fertilizers come from phosphate rock, a mineral mined in huge amounts of millions of tons in 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 acidic soils, where it serves the dual purpose of raising the pH. Rock phosphate fertilizers are becoming less common as raw rock provides relatively little phosphorus for its weight and transport costs make it more expensive than refined phosphate fertilizer.
Phosphate fertilizer in its liquid form can be easily applied to fields and crops.
The process by which phosphate rock is converted into phosphate fertilizer involves treatment with sulfuric acid; the result is often called “superphosphate.” This sulfuric acid treatment removes the phosphates from the raw ore and creates a water-soluble form. This is mixed with water to create a series of fertilizer-like compounds in a concentrated liquid form that is easy to apply to fields and crops.
Granular phosphate fertilizer contains high levels of phosphorus.
Water-soluble superphosphate 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 plant’s primary nutrients; these are commonly combined into a granular mixture and packaged for shipment. 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 indicated on the label by a series of three numbers separated by dashes. These numbers refer to the amounts of nitrogen, phosphorus, and potassium, respectively, and are usually represented by their individual chemical symbols N, P, and K.
A complete fertilizer can be labeled as having a 10-15-20 NPK formula. This means that the fertilizer contains 10% nitrogen by weight, 15% phosphorus by weight and 20% potassium by weight. The rest of the product is made from other ingredients, which may include other plant nutrients used in lesser amounts like sulfur, iron, magnesium and others.