Phosphorus biogeochemistry across a precipitation gradient in grasslands of central North America

TitlePhosphorus biogeochemistry across a precipitation gradient in grasslands of central North America
Publication TypeJournal Article
Year of Publication2010
AuthorsIppolito, JA, Blecker, SW, Freeman, CL, McCulley, RL, Blair, JM, Kelly, EF
JournalJournal of Arid Environments
Pagination954 -961
Accession NumberKNZ001301
KeywordsGrassland ecosystems, Phosphorus biogeochemistry, Sequential phosphorus extraction, Soil weathering

Soil P transformations and distribution studies under water limited conditions that characterize many grasslands may provide further insight into the importance of abiotic and biotic P controls within grass-dominated ecosystems. We assessed transformations between P pools across four sites spanning the shortgrass steppe, mixed grass prairie, and tallgrass prairie along a 400-mm precipitation gradient across the central Great Plains. Pedon total elemental and constituent mass balance analyses reflected a pattern of increased chemical weathering from the more arid shortgrass steppe to the more mesic tallgrass prairie. Soil surface A horizon P accumulation was likely related to increased biocycling and biological mining. Soluble P, a small fraction of total P in surface A horizons, was greatest at the mixed grass sites. The distribution of secondary soil P fractions across the gradient suggested decreasing Ca-bound P and increasing amounts of occluded P with increasing precipitation. Surface A horizons contained evidence of Ca-bound P in the absence of CaCO3, while in subsurface horizons the Ca-bound P was associated with increasing CaCO3 content. Calcium-bound P, which dominates in water-limited systems, forms under different sets of soil chemical conditions in different climatic regimes, demonstrating the importance of carbonate regulation of P in semi-arid ecosystems.