Title: Fertilizer Value of Phosphorus Extracted from Liquid Swine Wastewater Authors
Submitted to: American Society of Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: April 20, 2006
Publication Date: November 12, 2006
Citation: Bauer, P.J., Szogi, A.A., Vanotti, M.B. 2006. Fertilizer value of phosphorus extracted from liquid swine wastewater [abstract]. ASA-CSSA-SSSA 2006 International Meetings, November 12-16, 2006, Indianapolis, Indiana. 2006 CDROM. Technical Abstract: A precipitate of calcium phosphate is produced and recovered using a new treatment process developed for removal of P from swine wastewater. We conducted a greenhouse study to evaluate P availability and plant response to the recovered P material. Calcium phosphate precipitate (125 g P/kg) with particle sizes of 0.5-1 mm, precipitate with particles sizes of 1-2 mm diameter, and triple superphosphate (202 g P/kg) were mixed with soil (sandy soil texture, initial P content of 1.7 mg P per kg soil, pH 6.5) at rates of 0, 22, 44, 88, and 176 mg P per kg soil and placed in 15-cm diameter pots. Pots were watered (100 g water per kg soil) and incubated on greenhouse benches for 1 month before planting ryegrass (Lolium multiflorum Lam.) seeds. Plants were harvested by clipping approximately 2.5 cm above the soil surface at 2, 4, and 6 weeks after emergence. Dry weight and P concentration of the ryegrass tissues were measured at each clipping. The recovered P material with 1-2 mm sized particles did not substantially affect biomass or plant P concentration at any rate. Biomass increased with increasing P rate up to 44 g/kg for both the recovered P materials with 0.5-1 mm sized particles and for triple superphoshate, while tissue P concentration continued increasing up to 176 mg/kg for these two materials. Total P removal per pot by plants fertilized with 22 mg/kg of the 0.5-1 mm particle size was about 20% of that by plants fertilized with triple superphosphate at the rate. At the 44, 88, and 176 mg P/kg rates, P removal by plants for this treatment was about 60% of those fertilized with triple superphosphate. This initial study suggests this precipitate material may be an effective slow-release P fertilizer for plant production.