Quantification and bioavailability of scyllo-inositol hexakisphosphate in pasture soils

The recent identification of scyllo-inositol hexakisphosphate in alkaline soil extracts by solution 31P NMR spectroscopy allowed us to investigate this compound in soils by re-analyzing spectra from two previously published studies. Concentrations of scyllo-inositol hexakisphosphate in 29 temperate pasture soils from England and Wales ranged between 11 and 130 mg P kg−1 soil and accounted for between 4 and 15% of the soil organic phosphorus. The ratio of scyllo-inositol hexakisphosphate to myo-inositol hexakisphosphate ranged between 0.29 and 0.79. In a 10 month pot experiment with six grassland soils from New Zealand, growth of pine seedlings (Pinus radiata D. Don) decreased scyllo-inositol hexakisphosphate concentrations by between 10 and 46%. Growth of ryegrass (Lolium perenne L.) decreased scyllo-inositol hexakisphosphate in three low-nutrient soils by 5–21%, but increased it in three other soils by 11–16%. We conclude that scyllo-inositol hexakisphosphate is an important component of soil organic phosphorus with potential ecological significance.