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

• Published in: Journal of arid environments 2010-08, Vol.74 (8), p.954-961
• Main Authors: Ippolito, J.A., Blecker, S.W., Freeman, C.L., McCulley, R.L., Blair, J.M., Kelly, E.F.
• Format: Article
• Language: English
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; biogeochemistry; Biological and medical sciences; Calcium carbonate; Ecosystems; fractionation; Fundamental and applied biological sciences. Psychology; General aspects; Grasses; Grassland ecosystems; grassland soils; Grasslands; Horizon; phosphorus; Phosphorus biogeochemistry; Precipitation; semiarid soils; Sequential phosphorus extraction; Soil (material); soil chemical properties; soil nutrients; soil physical properties; Soil weathering; Steppes; Synecology; Terrestrial ecosystems; Transformations
• ISSN: 0140-1963; 1095-922X
• DOI: 10.1016/j.jaridenv.2010.01.003

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 CaCO 3, while in subsurface horizons the Ca-bound P was associated with increasing CaCO 3 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.