Jeq50409 928..937

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 soil) and non-composted manures (60 mg kg soil) and for the latter and the fertilizer (40 mg kg soil). However, the CPU was significantly higher for organic amendments than the control (24 mg kg 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. LAND APPLICATION of animal manures is coming under increasing scrutiny because of growing public concern over the long-term effects on soil P accumulation and potential contribution to surface water eutrophication (Sims et al., 2000). The spatial separation of crop and livestock production systems and the high cost of transporting manure have resulted in excessive land applications of manure in agricultural fields near confined feeding operations (e.g., beef cattle feedlots) (Kellogg et al., 2000). Composting, which is gaining increased acceptance in western Canada’s cattle feedlot industry, is one strategy to reduce total manure volume and mass. Composting allows transportation of manure over greater distances from areas of nutrient surplus (in the vicinity of feedlots) to areas of deficiency (Larney et al., 2000). Composting also improves the market value of feedlot manure as a soil amendment and fertilizer (DeLuca and DeLuca, 1997) and eliminates pathogens (Larney et al., 2003b) and weed seeds (Larney and Blackshaw, 2003) typically found in manure. There is growing interest in the use of organic amendments for reclamation of degraded soils. In Alberta, Canada alone, an estimated 40000 ha of land are disturbed by industrial activity (including oil and natural gas exploration, pipelines, gravel pits, and coal mines) annually (Janz, 1999). Recent research in southern Alberta has demonstrated the beneficial effects of manure and compost in restoring crop productivity to degraded soils (Larney et al., 2003a). Phosphorus content of non-composted and composted cattle manure can vary widely due to the influence of type of feeding operation, water content, type and amount of bedding, animal age, feed and supplements used, and duration of storage (Barnett, 1994; Dou et al., 2000). Composting results in higher P concentrations because P is conserved while CO2 and NH3 losses result in 30 to 50% reduction in mass of C and N (DeLuca and DeLuca, 1997). Although P-based manure loading rates and longterm applications are based primarily on total phosphorus (TP) content, it is the inorganic phosphorus (Pi) forms that directly determine plant uptake and runoff losses. Dissolved Pi is readily available for uptake by algae and aquatic plants and therefore presents an immeF. Zvomuya. F.J. Larney, H.H. Janzen, Agriculture and Agri-Food Canada, Lethbridge Research Centre, 5403 1st Avenue South, Lethbridge, AB, Canada T1J 4B1. B.L. Helgason, Land Resource Unit, Agriculture and Agri-Food Canada, 51 Campus Drive, Saskatoon, SK, Canada S7N 5A8. O.O. Akinremi, Department of Soil Science, University of Manitoba, Winnipeg, MB, Canada R3T 2N2. B.M. Olson, Alberta Agriculture, Food and Rural Development, 5401 1st Avenue South, Lethbridge, AB, Canada T1J 4V6. Lethbridge Research Centre Contribution no. 38705055. Received 26 Oct. 2005. *Corresponding author ([email protected]). Published in J. Environ. Qual. 35:928–937 (2006). Technical Reports: Waste Management doi:10.2134/jeq2005.0409 a ASA, CSSA, SSSA 677 S. Segoe Rd., Madison, WI 53711 USA Abbreviations: ACPU, amendment-derived cumulative phosphorus uptake; APR, apparent phosphorus recovery; CPU, cumulative phosphorus uptake; MKP, modified Kelowna-extractable phosphorus; OLS, ordinary least squares; OM, organic matter; Pi, inorganic phosphorus;PiH2O, totalwater-extractable inorganicphosphorus;PiHCl, total HCl-extractable inorganic phosphorus; PiHCO3, totalNaHCO3–extractable inorganic phosphorus; PiNaOH, total NaOH-extractable inorganic phosphorus; PLS, partial least squares; Po, organic phosphorus; PoH2O, total water-extractable organic phosphorus; PoHCl, total HCl-extractable organic phosphorus; PoHCO3, total NaHCO3–extractable organic phosphorus; PoNaOH, totalNaOH-extractableorganic phosphorus; Pres, residual phosphorus; PRESS, predicted residual sum of squares; SBM, straw-bedded manure; TC, total carbon; TP, total phosphorus; TPH2O, total water-extractable phosphorus; TPHCl, total HCl-extractable phosphorus;TPHCO3, totalNaHCO3–extractablephosphorus;TPi, total inorganic phosphorus; TPNaOH, total NaOH-extractable phosphorus; TPo, total organic phosphorus; VIP, variable importance on prediction; WBM, wood chip–bedded manure. R e p ro d u c e d fr o m J o u rn a l o f E n v ir o n m e n ta l Q u a lit y . P u b lis h e d b y A S A , C S S A , a n d S S S A . A ll c o p y ri g h ts re s e rv e d . 928 Published online April 26, 2006