Phosphorus Fractions in Grassland and Shrubland Soils at the Sevilleta National Wildlife Refuge

This study examined concentrations of organic and inorganic phosphorus in surface soils of a Bouteloua gracilis-Bouteloua eriopoda grassland and a Larrea tridentata shrubland in the northern Chihuahuan Desert, New Mexico, USA. In this desert, where grassland vegetation has a uniform spatial distribution and individual shrubs have a patchy distribution, vegetation strongly influences the locations and concentrations of soil nutrients.

Most studies of soil phosphorus (P) fractions in desert soils have focused on inorganic P fractions and have demonstrated the importance of geochemical controls on soil P cycling. This study addressed whether organic phosphorus, determined by the presence of different vegetation types, also contributes to soil P cycling. Within soils of similar age, topography, parent material, and climatic regime, samples were collected under and between vegetation and analyzed for P fractions following a modified sequential fractionation scheme.