QUANTITATIVE FRACTIONATION OF ORGANIC PHOSPHORUS COMPOUNDS IN SOME ALBERTA SOILS

Abstract

Soil samples from the A and B horizons of nine virgin profiles and from the A2 horizons of two of the profiles were analysed for organic phosphorus content. The nine profiles represented five of the major soil zones of Alberta. Organic phosphorus extracted with HCl and NaOH treatments was separated into three fractions using an anion exchange column. The three fractions contained unidentified phosphorus compounds, meso-inositol hexaphosphate and a supposed isomer of meso-inositol hexaphosphate respectively.The unidentified compounds in the A horizons contained the major proportion of the organic phosphorus. Of the two inositol hexaphosphate compounds measured, the supposed isomer was present in larger quantities than the meso form with the exception of the Hemaruka soil in which the meso form was slightly higher. The three fractions together accounted for only 54.0 per cent of the total organic phosphorus.The largest amounts of organic phosphorus in the B horizons also occurred in Fraction 1. However, in the B horizons this fraction accounted for 63.4 per cent of the total organic phosphorus in comparison to the 42.2 per cent in the first fraction of the A horizons. The total of the two inositol hexaphosphate compounds in the B horizons accounted for only 2.8 per cent of the total organic phosphorus while in the A horizons the same compounds accounted for 11.8 per cent of the total organic phosphorus. Of the 2.8 per cent organic phosphorus that was present as inositol hexaphosphate in the B horizons, the greatest proportion was in the meso form, while the reverse was true of the A horizons.The A3 horizons contained 6.9 per cent of the total organic phosphorus in the inositol hexaphosphate form, with the larger amount in the meso form.