title: Degree of phosphorus saturation of an Oxisol amended with biosolids in a long-term field experiment.
abstract: When applied to agricultural soils, phosphate fertilizers and the mineral or organic compounds present in solid and/or liquid waste may raise phosphorus (P) content and increase soil P saturation. The degree of phosphorus saturation (DPS) is a good indicator of potential P loss from agricultural soils. The purpose of this study was to calculate the DPS of samples from an Oxisol amended for 5 years with biosolids and mineral fertilizer. DPS was calculated based on P, iron, and aluminum extracted by ammonium oxalate and oxalic acid (DPSox) or by Mehlich-1 solution (DPSM1). Treatments included NPK mineral fertilization (175 kg ha(-1) of P), B1 = 19.02 t ha(-1) of biosolids (350 kg ha(-1) of P), B2 = 38.17 t ha(-1) of biosolids (703 kg ha(-1) of P), B3 = 76.26 t ha(-1) of biosolids (1,405 kg ha(-1) of P), and a control (no P added). Water-extractable P (WEP) was also measured. Critical levels of DPSox and DPSM1 (21 and 24 %, respectively) were only achieved in the topsoil (0-0.1 m) at the highest biosolid dose. Concentration of WEP was positively correlated to DPSox and DPSM1. The DPSM1 method may be an alternative to DPSox for assessing the environmental risk of P loss from soil into surface runoff.
authors.affiliation: Department of Soil Science, ESALQ, University of São Paulo, C.P. 09, Piracicaba, SP, 13418-900, Brazil, alleoni@usp.br.
authors.forename: Luís Reynaldo Ferracciú
authors.initials: LR
authors.lastname: Alleoni
authors.forename: Antonio Rodrigues
authors.initials: AR
authors.lastname: Fernandes
authors.forename: Murilo
authors.initials: M
authors.lastname: de Campos
mesh_terms: D000383:Agriculture; D004784:Environmental Monitoring; D052918:Environmental Restoration and Remediation; D005308:Fertilizers; D009930:Organic Chemicals; D010758:Phosphorus / Q000032:analysis*; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000032:analysis*; D014865:Waste Disposal, Fluid
chemical_list: D005308:Fertilizers; D009930:Organic Chemicals; D012987:Soil; D012989:Soil Pollutants; D010758:Phosphorus