5. The Phosphorus cycle

List the phosphorus cycle - 7

• Phosphate ions in rocks are released into the soil by weathering.

• Phosphate ions are taken into the plants through the roots. Mycorrhizae increase the rate of this

• Phosphate ions are transferred through the food chain as animals eat the plants and eat each other.

• Phosphate ions are lost from the animals in waste products.

• When plants die, saprobiants are involved in breaking down the organic compounds, releasing phosphate ions into the soil for assimilation by plants.

• Weathering of rocks also releases phosphate ions into seas, lakes and rivers. This is taken up by the aquatic producers, such as algae, and passed along the food chain to birds.

• The waste produced by sea birds is known as guano and contains a high proportion of phosphate ions. Guano returns a significant amount of phosphate ions to soils (often used as a natural fertiliser).

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