title: Phosphorus sequestration by chemical amendments to reduce leaching from wastewater applications.
abstract: Phosphorus-immobilizing amendments can be useful in minimizing P leaching from high P soils that may be irrigated with wastewater. This study tested the P-binding ability of various amendment materials in a laboratory incubation experiment and then tested the best amendment in a field setup using drainage lysimeters. The laboratory experiment involved incubating 100-g samples of soil (72 mg kg(-1) water-extractable phosphorus, WEP) with various amendments at different rates for 63 d at field moisture capacity and 25 degrees C. The amendments tested were alum [Al2SO4)3.14H2O], ferric chloride (FeCl3), calcium carbonate (CaCO3), water treatment residual (WTR), and sugarbeet lime (SBL). Ferric chloride and alum at rates of 1.5 and 3.9 g kg(-1), respectively, were the most effective amendments that decreased WEP to 20 mg kg(-1), below which leaching has previously been shown to be low. Alum (1.3 kg m(-2)), which is less sensitive to redox conditions, was subsequently tested under field conditions, where it reduced WEP concentration in the 0- to 0.15-m layer from 119 mg kg(-1) on Day 0 to 36.1 mg kg(-1) (85% decrease) on Day 41. Lysimeter breakthrough tests using tertiary-treated potato-processing wastewater (mean total phosphorus [TP] = 3.4 mg L(-1)) showed that alum application reduced leachate TP and soluble reactive phosphorus (SRP) concentrations by 27 and 25%, respectively. These results indicate that alum application may be an effective strategy to immobilize P in high P coarse-textured soils. The relatively smaller decreases in TP and SRP in the leachate compared to WEP suggest some of the P may be coming from depths below 0.2 m. Thus, to achieve higher P sequestration, deeper incorporation of the alum may be necessary.
authors.affiliation: Lethbridge Research Centre, Agriculture and Agri-Food Canada, 5403 - 1 Avenue S., Lethbridge, AB, Canada T1J 4B1.
authors.forename: Francis
authors.initials: F
authors.lastname: Zvomuya
authors.forename: Carl J
authors.initials: CJ
authors.lastname: Rosen
authors.forename: Satish C
authors.initials: SC
authors.lastname: Gupta
mesh_terms: D004553:Electric Conductivity; D006863:Hydrogen-Ion Concentration; D007220:Industrial Waste; D010758:Phosphorus / Q000302:isolation & purification*; D012987:Soil; D014867:Water
chemical_list: D007220:Industrial Waste; D012987:Soil; D014867:Water; D010758:Phosphorus