Complex Forms of Soil Organic Phosphorus-A Major Component of Soil Phosphorus.
Phosphorus (P) is an essential element for life, an innate constituent of soil organic matter, and a major anthropogenic input to terrestrial ecosystems. The supply of P to living organisms is strongly dependent on the dynamics of soil organic P. However, fluxes of P through soil organic matter remain unclear because only a minority (typically <30%) of soil organic P has been identified as recognizable biomolecules of low molecular weight (e.g., inositol hexakisphosphates). Here, we use (31)P nuclear magnetic resonance spectroscopy to determine the speciation of organic P in soil extracts fractionated into two molecular weight ranges. Speciation of organic P in the high molecular weight fraction (>10 kDa) was markedly different to that of the low molecular weight fraction (<10 kDa). The former was dominated by a broad peak, which is consistent with P bound by phosphomonoester linkages of supra-/macro-molecular structures, whereas the latter contained all of the sharp peaks that were present in unfractionated extracts, along with some broad signal. Overall, phosphomonoesters in supra-/macro-molecular structures were found to account for the majority (61% to 73%) of soil organic P across the five diverse soils. These soil phosphomonoesters will need to be integrated within current models of the inorganic-organic P cycle of soil-plant terrestrial ecosystems.
Soils Group, School of Agriculture, Food and Wine and Waite Research Institute, The University of Adelaide , Urrbrae, 5064, South Australia, Australia.|School of Environmental and Rural Science, University of New England , Armidale, 2350, New South Wales, Australia.
Timothy I
TI
McLaren
Soils Group, School of Agriculture, Food and Wine and Waite Research Institute, The University of Adelaide , Urrbrae, 5064, South Australia, Australia.
Ronald J
RJ
Smernik
Soils Group, School of Agriculture, Food and Wine and Waite Research Institute, The University of Adelaide , Urrbrae, 5064, South Australia, Australia.|CSIRO Land and Water, Glen Osmond 5064, South Australia, Australia.
Mike J
MJ
McLaughlin
Soils Group, School of Agriculture, Food and Wine and Waite Research Institute, The University of Adelaide , Urrbrae, 5064, South Australia, Australia.|CSIRO Agriculture, Glen Osmond, 5064, South Australia, Australia.
Therese M
TM
McBeath
CSIRO Land and Water, Glen Osmond 5064, South Australia, Australia.
Jason K
JK
Kirby
CSIRO Agriculture, GPO Box 1600, Canberra, 2601, Australian Capital Territory, Australia.
Richard J
RJ
Simpson
School of Environmental and Rural Science, University of New England , Armidale, 2350, New South Wales, Australia.
Christopher N
CN
Guppy
Soils Group, School of Agriculture, Food and Wine and Waite Research Institute, The University of Adelaide , Urrbrae, 5064, South Australia, Australia.
Ashlea L
AL
Doolette
CSIRO Agriculture, GPO Box 1600, Canberra, 2601, Australian Capital Territory, Australia.
Alan E
AE
Richardson
D017753:Ecosystem; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008970:Molecular Weight; D010758:Phosphorus / Q000032:analysis / Q000737:chemistry*; D010759:Phosphorus Isotopes; D012987:Soil / Q000737:chemistry*
D010759:Phosphorus Isotopes; D012987:Soil; D010758:Phosphorus