phosphorus cycle

• phosphorus is a component of DNA, RNA cell membranes and proteins
• there are no gaseous resovoirs of phosphorus
• plants absorb phosphates that they will use in metabolic reactions
• plants aren't good at absorbing phosphates so they likely have symbiotic relationships with fungi
• fungi have an extensive network of fungal hyphae in soil, this increases surface area and hence absorption rate
• breakdown of phosphorylated proteins in dead organic matter releases phosphates
• sedimentation: dead phosphorus in organisms become incorporated into sediments, this is no longer available for organisms
• processes that mobilise phosphorous and make it available for organism are slow
• phosphorus in marine sediments may not become available until continental drift forms new mountain ranges and weathering then releases phosphates
• mining of phosphate rocks: phosphorus is mostly mined as calcium phosphate rocks then are treated producing ammonium phosphate which has a higher solubility
• fertiliser use mobilises phosphorus compounds into the environment in more soluble forms
• fertiliser use can increase crop production and contribute to eutrophication
• crop breeding programmes increase the efficiency of phosphate absorption into plants