Characterization of phosphorus fractions in mountain soils of the Bavarian Alps by 31P NMR spectroscopy

Abstract
NaOH‐extracts from different soils of the alpine and shrub zones at the Schneibstein (Nationalpark Berchtesgaden) between 1790–2275 m were studied using 31P NMR spectroscopy. NaOH (0.5 M) dissolved 29–49% of Pt. Orthophosphate monoesters were the dominant fraction (41–79%). Orthophosphate diesters comprised 10–20%. A higher diester content (36%) was found in a hydromorphic soil. Inorganic phosphate comprised 5–27%, depending on soil pH. So, in acid horizons (pH 4.45 and 5.05) 27 and 23% were detected, whereas in horizons with higher pH (> 6) only small amounts (5–8%) were found. Pyrophosphate and polyphosphates were found in traces. Phosphonates (ca. 6%) occurred mainly in acid soils.