Phosphorus speciation by 31P NMR spectroscopy in bracken (Pteridium aquilinum (L.) Kuhn) and bluebell (Hyacinthoides non-scripta (L.) Chouard ex Rothm.) dominated semi-natural upland soil

Access to P species is a driver for plant community composition based on nutrient acquisition. Here we investigated the distribution and accumulation of soil inorganic P (Pi) and organic P (Po) forms in a bracken and bluebell dominated upland soil for the period between bluebell above ground dominance until biomass is formed from half bluebells and half bracken. Chemical characterisation and P-31 Nuclear Magnetic Resonance spectroscopy was used to determine the organic and inorganic P species. Total P concentration in soils was 0.87 g kg(-1), while in plants (above- and below-ground parts) total P ranged between 0.84-4.0 g kg(-1) and 0.14-2.0 g kg(-1) for bluebell and bracken, respectively. The P speciation in the plant samples was reflected in the surrounding soil. The main forms of inorganic P detected in the NaOH-EDTA soil extracts were orthophosphate (20.0-31.5%), pyrophosphate (0.6-2.5%) and polyphosphate (0.4-7.0%). Phytate (myo-IP6) was the most dominant organic P form (23.6-40.0%). Other major peaks were scyllo-IP6 and alpha-and beta-glycerophosphate (glyP). In bluebells and bracken the main P form detected was orthophosphate ranging from(21.7-80.4%) and 68.5-81.1%, in above-ground and below-ground biomass, respectively. Other detected forms include alpha-glyP (4.5-14.4%) and beta-glyP (0.9-7.7%) in bluebell, while in bracken they were detected only in stripe and blade in ranges of 2.5-5.5% and 4.4-9.6%, respectively. Pyrophosphate, polyphosphate, scyllo-IP6, phosphonates, found in soil samples, were not detected in any plant parts. In particular, the high abundance of phytate in the soil and in bluebell bulbs, may be related to a mechanism through which bluebells create a recalcitrant phosphorus store which form a key part of their adaptation to nutrient poor conditions. (C) 2016 Elsevier B.V. All rights reserved.