justify that phosphorus cycle is an incomplete cycle

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The phosphorous cycle is the movement of phosphorous between rocks, sediments, plants and animals. Phosphorous is present in less amounts in soil and is usually applied through external source i.e fertilizers. Phosphorous cycle is usually incomplete because of the following reasons:

1. The natural cycle of phosphorous is very slow. It takes lots of time for phosphorous to get back into minerals of rocks, sediments from the dead animals and plants. Also it remains in rocks and sediments for millions of years before being released again. However, even though this cycle is slow but may be usually complete.
2. The human driven cycle where phosphorous is mined from rocks and applied as fertiliser may not return back to the rocks and is lost by runoff, erosion and crop harvesting. Hence is incomplete.

 
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