156-10 Is P in the Coarse Soil Fraction Related to Soil Organic P Mineralization Measured By Isotopic Dilution?.

Poster Number 1322

See more from this Division: SSSA Division: Soil Fertility & Plant Nutrition
See more from this Session: Ph.D. Graduate Student Poster Competition

Monday, November 16, 2015
Minneapolis Convention Center, Exhibit Hall BC

Nicolas Wyngaard, University of Georgia, Athens, GA, Miguel L. Cabrera, Crop and Soil Sciences Department, University of Georgia-Athens, Athens, GA and Else K B√ľnemann, Institute of Agricultural Sciences, Swiss Federal Institute of Technology Zurich (ETH), Lindau, Switzerland
Poster Presentation
  • Poster-Nicolas Wyngaard Poster 2015 MC Edits.pdf (794.8 kB)
  • Abstract:
    Measuring soil organic phosphorus (Po) mineralization would be helpful to improve fertilizer recommendations. However, the only reliable method to measure Po mineralization is based on isotopic dilution experiments, which are expensive and time consuming. A proposed method to estimate P mineralization is the quantification of P in the coarse fraction of the soil (CF). The aim of this study was to evaluate if P in the CF can effectively predict Po mineralization. To this end, soil samples from three North American long-term field experiments with different fertilization treatments (non-fertilized, mineral P fertilizer, poultry litter) for more than 10 years were analyzed. Soil samples were physically fractioned into the CF and the fine fraction (FF), and total P (Pt), Po, and total carbon (Ct) were determined in each fraction. A 13-day-incubation experiment was also conducted in which soil respiration as well as gross and net Po mineralization rates were determined. The cumulative gross Po mineralized over 13 days ranged from 7.3 to 38.6 mg P kg-1, while Pt in the CF varied between 9.7 and 90.7 mg P kg-1 and Po in the CF between 7.2 and 17.7 mg kg-1. No association between Pt in CF and mineralized Po was observed. However, a significant linear relationship between Po in the CF and mineralized Po was observed after 6 days (R2:0.79) and a quadratic one after 13 days of incubation(R2:0.90). Additionally, mineralized Po could also be predicted from C respiration (R2:0.52), and this model was significantly improved by incorporating the Ct:Po ratio of the CF (R2:0.77), but not by the Ct:Po of the FF (R2:0.54). Our results suggest that the quantification of Po in the CF is a promising non-isotopic alternative to estimate basal Po mineralization.

    See more from this Division: SSSA Division: Soil Fertility & Plant Nutrition
    See more from this Session: Ph.D. Graduate Student Poster Competition