title: Predicting phosphorus availability from soil-applied composted and non-composted cattle feedlot manure.
abstract: Prediction of phosphorus (P) availability from soil-applied composts and manure is important for agronomic and environmental reasons. This study utilized chemical properties of eight composted and two non-composted beef cattle (Bos taurus) manures to predict cumulative phosphorus uptake (CPU) during a 363-d controlled environment chamber bioassay. Ten growth cycles of canola (Brassica napus L.) were raised in pots containing 2 kg of a Dark Brown Chernozemic clay loam soil (fine-loamy, mixed, Typic Haploboroll) mixed with 0.04 kg of the amendments. Inorganic P fertilizer (KH2PO4) and an unamended control were included for comparison. All treatments received a nutrient solution containing an adequate supply of all essential nutrients, except P, which was supplied by the amendments. Cumulative P uptake was similar for composted (74 mg kg-1 soil) and non-composted manures (60 mg kg-1 soil) and for the latter and the fertilizer (40 mg kg-1 soil). However, the CPU was significantly higher for organic amendments than the control (24 mg kg-1 soil) and for composted manure than the fertilizer. Apparent phosphorus recovery (APR) from composted manure (24%) was significantly lower than that from non-composted manure (33%), but there was no significant difference in APR between the organic amendments and the fertilizer (27%). Partial least squares (PLS) regression indicated that only two parameters [total water-extractable phosphorus (TPH2O) and total phosphorus (TP) concentration of amendments] were adequate to model amendment-derived cumulative phosphorus uptake (ACPU), explaining 81% of the variation in ACPU. These results suggest that P availability from soil-applied composted and non-composted manures can be adequately predicted from a few simple amendment chemical measurements. Accurate prediction of P availability and plant P recovery may help tailor manure and compost applications to plant needs and minimize the buildup of bioavailable P, which can contribute to eutrophication of sensitive aquatic systems.
authors.affiliation: Agriculture and Agri-Food Canada, Lethbridge Research Centre, 5403 1st Avenue South, Lethbridge, AB, Canada T1J 4B1.
authors.forename: Francis
authors.initials: F
authors.lastname: Zvomuya
authors.forename: Bobbi L
authors.initials: BL
authors.lastname: Helgason
authors.forename: Francis J
authors.initials: FJ
authors.lastname: Larney
authors.forename: H Henry
authors.initials: HH
authors.lastname: Janzen
authors.forename: Olalekan O
authors.initials: OO
authors.lastname: Akinremi
authors.forename: Barry M
authors.initials: BM
authors.lastname: Olson
mesh_terms: D000818:Animals; D018533:Biomass; D002417:Cattle; D016018:Least-Squares Analysis; D008372:Manure; D010758:Phosphorus / Q000032:analysis*; D012987:Soil / Q000032:analysis*
chemical_list: D008372:Manure; D012987:Soil; D010758:Phosphorus