Land use and soil factors affecting accumulation of phosphorus species in temperate soils

Publication date: November 2015
Source:Geoderma, Volumes 257–258
Author(s): Marc I. Stutter , Charles A. Shand , Timothy S. George , Martin S.A. Blackwell , Liz Dixon , Roland Bol , Regina L. MacKay , Alan E. Richardson , Leo M. Condron , Philip M. Haygarth
Data on the distribution of phosphorus (P) species in soils with differing land uses and properties are essential to understanding environmental P availability and how fertiliser inputs, cropping and grazing affect accumulation of soil inorganic P (Pi) and organic P (Po) forms. We examined thirty-two temperate soils (with soil organic C concentrations 12–449gCkg⁻¹ and total P 295–3435mgPkg⁻¹) for biogeochemical properties of soil C, reactive surfaces and P by common indices and ³¹P-NMR spectroscopy on NaOH–EDTA extracts for P species. Arable soil P was dominated by inorganic orthophosphate (276–2520mgPkg⁻¹), >monoester P (105–446mgPkg⁻¹). The limited diesters, polyphosphates and microbial P in arable soils suggest that cropping and fertiliser inputs limit ecosystem microbial functions and P diversity. Intensive grassland had inorganic orthophosphate concentrations (233–842mgPkg⁻¹) similar to monoesters (200–658mgPkg⁻¹)>diesters (0–50mgPkg⁻¹) and polyphosphates (1–78mgPkg⁻¹). As grazing became more extensive P in semi-natural systems was dominated by organic P, including monoesters (37–621mgPkg⁻¹) and other diverse forms; principally diester (0–102mgPkg⁻¹) and polyphosphates (0–108mgPkg⁻¹). These were related to SOC, water extractable organic carbon (WEOC) and microbial P, suggesting strong microbially-mediated processes. A number of abiotic and biotic related processes appeared to control accumulation of different soil P species and gave considerable variability in forms and concentrations within land use groups. The implications are that to increase agricultural P efficiencies mechanisms to utilise both soil Pi and Po are needed and that specific management strategies may be required for site-specific circumstances of soil C and reactive properties such as Fe and Al complexes.