『Abstract
This study examined the concentration 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 the grassland vegetation has a uniform spatial distribution
and individual shrubs have a patchy spatial distribution across
the landscape, vegetation strongly influences the distribution
of soil nutrients. Most studies of soil phosphorus fractions in
desert soils have focused primarily on inorganic P fractions and
have demonstrated the importance of geochemical controls on soil
P cycling. The research presented here addressed the question
of 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. Most soil inorganic P was found in the HCl- and cHCl-extractable
forms in both the grassland and shrubland soils, indicating CaCO3 control over phosphorus availability. In contrast,
most soil organic P was bound to al and Fe minerals. Labile, plant-available
P fractions summed to 9.5％ of total P in the grassland and 6.1％
in the shrubland. Organic P comprised 13.3％ of the total phosphorus
pool in the grassland and 12.0％ in the shrubland. Our results
show that the organic P pool may represent an important, yet often
overlooked, source of P in semiarid ecosystems.
Key words: desert soils; New Mexico; sequential P fractionation;
soil organic phosphorus; soil phosphorus』
Introduction
Methods
Field collections
Laboratory analyses
Statistical analyses
Results
Discussion
Acknowledgements
References
※リンの連続抽出法は、Hedleyの方法を修正したもの（Tiessen et al., 1984とTiessen & Moir, 1993）