title: Phosphate stable oxygen isotope variability within a temperate agricultural soil.
abstract: In this study, we conduct a spatial analysis of soil total phosphorus (TP), acid extractable phosphate (PO4) and the stable oxygen (O) isotope ratio within the PO4molecule (δ18OPO4) from an intensively managed agricultural grassland site. Total P in the soil was found to range from 736 to 1952 mg P kg- 1, of which between 12 and 48% was extractable using a 1 M HCl (HClPO4) solution with the two variables exhibiting a strong positive correlation. The δ18OPO4of the extracted PO4ranged from 17.0 to 21.6‰ with a mean of 18.8‰ (± 0.8). While the spatial variability of Total P has been researched at various scales, this is the first study to assess the variability of soil δ18OPO4at a field-scale resolution. We investigate whether or not δ18OPO4variability has any significant relationship with: (i) itself with respect to spatial autocorrelation effects; and (ii) HClPO4, elevation and slope - both globally and locally. Results indicate that δ18OPO4was not spatially autocorrelated; and that δ18OPO4was only weakly related to HClPO4, elevation and slope, when considering the study field as a whole. Interestingly, the latter relationships appear to vary in strength locally. In particular, the δ18OPO4to HClPO4relationship may depend on the underlying soil class and/or on different field managements that had operated across an historical north-south field division of the study field, a division that had been removed four years prior to this study.
authors.affiliation: Rothamsted Research, North Wyke, Okehampton, Devon EX20 2SB, United Kingdom.
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Granger
authors.affiliation: Rothamsted Research, North Wyke, Okehampton, Devon EX20 2SB, United Kingdom.
authors.forename: Paul
authors.initials: P
authors.lastname: Harris
authors.affiliation: Rothamsted Research, North Wyke, Okehampton, Devon EX20 2SB, United Kingdom.
authors.forename: Sabine
authors.initials: S
authors.lastname: Peukert
authors.affiliation: Queen's School of Engineering, University of Bristol, Senate House, Tyndall Avenue, Bristol BS8 1TH, United Kingdom.
authors.forename: Rongrong
authors.initials: R
authors.lastname: Guo
authors.affiliation: Institute of Agricultural Sciences, ETH Zurich, Research Station Eschikon 33, 8315 Lindau, Switzerland.
authors.forename: Federica
authors.initials: F
authors.lastname: Tamburini
authors.affiliation: Rothamsted Research, North Wyke, Okehampton, Devon EX20 2SB, United Kingdom.
authors.forename: Martin S A
authors.initials: MS
authors.lastname: Blackwell
authors.affiliation: Queen's School of Engineering, University of Bristol, Senate House, Tyndall Avenue, Bristol BS8 1TH, United Kingdom.
authors.forename: Nicholas J K
authors.initials: NJ
authors.lastname: Howden
authors.affiliation: Rothamsted Research, West Common, Harpenden, Hertfordshire, AL5 2JQ, United Kingdom.
authors.forename: Steve
authors.initials: S
authors.lastname: McGrath
keywords: GW model; Grassland; North Wyke farm platform; Phosphorus; Spatial analysis