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Phosphorus Speciation in Hyperarid Soils: Insights from 31P NMR Analysis in the Atacama Desert.

Year: 2025
Type: preprint
Abstract: Phosphorus (P) speciation in hyperarid soils remains poorly characterized, particularly across environmental moisture gradients. The Atacama Desert in northern Chile, one of the driest regions on Earth, offers a natural laboratory to investigate P dynamics under extreme aridity. This study aimed to determine the forms and distribution of phosphorus in surface soils along two contrasting transects: the inland Aroma transect, with minimal Andean precipitation, and the coastal Paposo transect, influenced by marine fog and past localized moisture inputs from rare precipitation. Soil samples from one vegetated site and several unvegetated microsites were analyzed using solution-state ³¹P nuclear magnetic resonance (NMR) spectroscopy to identify inorganic and organic P forms. Orthophosphate was the dominant form across all sites, comprising over 95% of total P in most samples. Organic phosphorus (Po) was only detected at a mid-elevation vegetated site in Paposo (1450 m), where it accounted for over 30% of total P along with high extractable P concentrations and spectral signals for phosphomonoesters, phosphonates, and polyphosphates. These findings confirm that inorganic P predominates across hyperarid soils, while biological P cycling is restricted to microenvironments receiving localized and intermittent moisture. This study provides the first comparative ³¹P NMR-based assessment of phosphorus speciation across the Atacama Desert and contributes new insights into nutrient stability and transformation in extreme dryland soils. The findings are critical for understanding phosphorus cycling under expanding global aridity and the influence of microclimatic moisture on nutrient biogeochemistry.
DOI: 10.22541/au.175709062.29778595/v1
Language: English
Subfield: Soil Science
Open Access status: gold
OpenAlex ID: W4414011803
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