Massive machines are used to recover phosphate rock from Florida
Early sources of P were limited to animal manure, which did not supply any new nutrients, but merely allowed them to be transported from one area to another. The first commercial fertilizer became available when it was discovered that adding acid to animal bones would chemically unlock the phosphate and make it available for plant uptake.
|Early advertisement for superphosphate|
Phosphate rock is the raw material now used in commercial fertilizer production. Phosphate rock is extracted from the earth in many countries. Most of the phosphate rock is used for fertilizer production, with smaller amounts going to various industrial uses. Although phosphate rock is a limited natural resource, at current rates of use the world phosphate rock reserves and resources should be adequate for the foreseeable future.
Phosphate has many important functions in plants. Perhaps the most noted roles are in photosynthesis, respiration, energy storage and transfer, cell division, and cell enlargement. Adequate phosphate also promotes early root formation and growth.
Plants absorb most of their P as the primary orthophosphate ion (H2PO4-). Smaller amounts of secondary orthophosphate ion (HPO42-) are taken up. Other forms of P can be utilized, but in much smaller quantities than orthophosphate.
There are many excellent sources of phosphate fertilizer. The selection of a particular product depends on price, physical characteristics, and nutrients accompanying the phosphate. Agronomic studies have shown that there is no significant difference in plant response to common phosphate fertilizers if they are used properly. The most common fertilizers include:
• Diammonium phosphate (DAP) – DAP is the world’s most widely used P fertilizer. It is made from two common constituents in the fertilizer industry and it is popular because of its relatively high nutrient content and its excellent physical properties.
|Molecular structure of diammonium phosphate|
|Diammonium phosphate fertilizer|
|Molecular structure of monoammonium phosphate|
|Monoammonium phosphate fertilizer|
|Polyphosphate fluid fertilizer|
A visual tour of the phosphate production process can be seen at this URL: http://info.ipni.net/phosphatetech