title: The effect of pH on phosphorus availability and speciation in an aquaponics nutrient solution.
abstract: The interaction between the main ions in aquaponics nutrient solutions affects chemical composition and availability of nutrients, and nutrient uptake by plant roots. This study determined the effect of pH on phosphorus (P) speciation and availability in an aquaponics nutrient solution and used Visual MINTEQ to simulate P species and P activity. In both experimental and simulated results, P availability decreased with increase in pH of aquaponics nutrient solutions. According to simulations, P binds to several cations leaving less free phosphate ions available in solution. High pH values resulted in the formation of insoluble calcium phosphate species. The study also demonstrated the importance of organic matter and alkalinity in keeping free phosphate ions in solution at high pH ranges. It is recommended though that pH in aquaponics systems is maintained at a 5.5-7.2 range for optimal availability and uptake by plants.
authors: Department of Soil Water and Environmental Science, The University of Arizona, P.O. Box 210038, Tucson, AZ 85721-0038, United States. Electronic address: bcerozi@email.arizona.edu.
authors: Brunno da Silva
authors: BDS
authors: Cerozi
authors: Department of Soil Water and Environmental Science, The University of Arizona, P.O. Box 210038, Tucson, AZ 85721-0038, United States.
authors: Kevin
authors: K
authors: Fitzsimmons
mesh_terms: D000818:Animals; D017756:Aquaculture / Q000379:methods*; D001682:Biological Availability; D002118:Calcium / Q000378:metabolism; D002412:Cations / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D018527:Hydroponics / Q000379:methods*; D008956:Models, Chemical; D010710:Phosphates / Q000378:metabolism; D010758:Phosphorus / Q000378:metabolism / Q000493:pharmacokinetics*; D018517:Plant Roots / Q000378:metabolism*; D012996:Solutions / Q000737:chemistry; D017210:Tilapia
chemical_list: D002412:Cations; D010710:Phosphates; D012996:Solutions; D010758:Phosphorus; D002118:Calcium
keywords: Aquaponics; Availability; Phosphorus; Speciation; pH