title: Struvite: a slow-release fertiliser for sustainable phosphorus management?
abstract: OBJECTIVE
  Recycled sources of phosphorus (P), such as struvite extracted from wastewater, have potential to substitute for more soluble manufactured fertilisers and help reduce the long-term threat to food security from dwindling finite reserves of phosphate rock (PR). This study aimed to determine whether struvite could be a component of a sustainable P fertiliser management strategy for arable crops.
  
  
  METHODS
  A combination of laboratory experiments, pot trials and mathematical modelling of the root system examined the P release properties of commercial fertiliser-grade struvite and patterns of P uptake from a low-P sandy soil by two different crop types, in comparison to more soluble inorganic P fertilisers (di-ammonium phosphate (DAP) and triple super phosphate (TSP)).
  
  
  RESULTS
  Struvite had greatly enhanced solubility in the presence of organic acid anions; buckwheat, which exudes a high level of organic acids, was more effective at mobilising struvite P than the low level exuder, spring wheat. Struvite granules placed with the seed did not provide the same rate of P supply as placed DAP granules for early growth of spring wheat, but gave equivalent rates of P uptake, yield and apparent fertiliser recovery at harvest, even though only 26 % of struvite granules completely dissolved. Fertiliser mixes containing struvite and DAP applied to spring wheat have potential to provide both optimal early and late season P uptake and improve overall P use efficiency.
  
  
  CONCLUSIONS
  We conclude that the potential resource savings and potential efficiency benefits of utilising a recycled slow release fertiliser like struvite offers a more sustainable alternative to only using conventional, high solubility, PR-based fertilisers.
authors.affiliation: School of Environment, Natural Resources and Geography, Deiniol Road, Bangor, Gwynedd LL57 2UW UK.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Talboys
authors.affiliation: Institute for Complex Systems Simulation, University of Southampton, Southampton, SO17 1BJ UK.
authors.forename: James
authors.initials: J
authors.lastname: Heppell
authors.affiliation: Faculty of Engineering and the Environment, University of Southampton, Southampton, SO17 1BJ UK.
authors.forename: Tiina
authors.initials: T
authors.lastname: Roose
authors.affiliation: School of Environment, Natural Resources and Geography, Deiniol Road, Bangor, Gwynedd LL57 2UW UK.
authors.forename: John R
authors.initials: JR
authors.lastname: Healey
authors.affiliation: School of Environment, Natural Resources and Geography, Deiniol Road, Bangor, Gwynedd LL57 2UW UK.
authors.forename: Davey L
authors.initials: DL
authors.lastname: Jones
authors.affiliation: School of Environment, Natural Resources and Geography, Deiniol Road, Bangor, Gwynedd LL57 2UW UK.
authors.forename: Paul J A
authors.initials: PJ
authors.lastname: Withers
keywords: Buckwheat; Fertiliser; Organic acids; Phosphorus; Root system modelling; Struvite; Wheat