Phosphorus Fractions in Soils of Taylor Valley, Antarctica

Abstract

Phosphorus studies in the cold desert ecosystem of the Antarctic Dry Valleys have been largely confined to stream sediments and orthinogenic regions. Expanding P studies to soils may augment the understanding of P biogeochemistry and habitat suitability in this extreme environment. Our objectives were to examine P fractionation in Antarctic Dry Valley soils and sediments and compare their relationship to other soil biogeochemical data. Samples were obtained along transects perpendicular to the Harnish and Priscu streams in Lake Fryxell and Lake Bonney basins, respectively. We utilized a sequential inorganic P extraction procedure, analyzing for a series of labile through resistant P fractions. We further analyzed soils for labile organic P and biomass P. Results showed the amount of inorganic P increased from soluble to Ca-bound P at both sites, with greater weathering of P-bearing minerals at the Fryxell site inferred from the greater P levels found in most fractions as compared with the Bonney site. Fryxell site soluble P findings correlated positively with the Al-bound phase, possibly facilitating P availability to microfauna. The P fraction distribution at both the Fryxell and Bonney sites fits the general relationship between weathering intensity and P distribution of other arid ecosystems.

Biogeochemical stoichiometry of Antarctic Dry Valley ecosystems

“…In contrast to ancient, saline soils, young soils had low inorganic N concentrations, but high soil P (Figure 2). Calcium‐bound PO 4 −3 pools dominate soil P budgets for all soils reported in Taylor Valley [ Blecker et al , 2006], indicating that while P is abundant in bulk soils, relatively little of it is directly available to biota. The high P content of the Fryxell basin is associated with the youngest glacial tills in Taylor Valley [ Campbell and Claridge , 1987; Gudding , 2003].…”

Soil phosphorus cycling in an Antarctic polar desert

“…2; Table 2). Biogeochemical cycling in dry valley soils is constrained by low rates of chemical weathering and biotic potential for immobilization and transformation of nutrients (Barrett et al, 2002;Gooseff et al, 2002;Maurice et al, 2002;Blecker et al, 2006), presumably due to persistently low temperatures and limited availability of liquid water. Lajtha and Schlesinger (1988) drew similar conclusions about P dynamics in the Jornada Basin of the U.S. Chihuahuan Desert, where Cabound P comprises the majority of the total soil P budget.…”

“…chemical weathering, biological cycling, retention within the soil), which have varied in magnitude and duration among sites of different age and climate conditions (Gudding, 2003;Blecker et al, 2006). However, in systems where geochemical cycling is constrained by physical factors, geologic legacies may play a larger role than in situ processing in determining contemporary conditions Burkins et al, 2000).…”

“…Soils occurring on these tills represent the largest pool of P in the dry valleys and, although rates of P transport across landscapes remain unquantified (Barrett et al, 2007), it is likely that soils and sediments adjacent to streams and lakes are important sources of available P to these aquatic ecosystems. Little is known about controls over soil and sediment P dynamics though concentrations of available P are not likely to be limiting relative to requirements of soil microbial biomass and biological activity (Blecker et al, 2006;Barrett et al, 2006a).…”

Fate of Fertilizer P in Soils: Inorganic Pathway

“…In cold desert soils of Antarctica, soil minerals have undergone only minimal chemical weathering, and upon fractionation of P as much as 300-400 mg kg −1 (95-99 % of P) was found as "Ca-P" extractable with H 2 SO 4 (Blecker et al 2006). Kaila (1964) investigated P reserves of rather young (<10,000 years) Finnish soils according to the Chang and Jackson procedure and identified "Ca-P" as the most abundant in virgin mineral soils (Table 2).…”