Pools, transformations, and sources of P in high-elevation soils: Implications for nutrient transfer to Sierra Nevada lakes

In high-elevation lakes of the Sierra Nevada (California), increases in P supply have been inferred from shifts in P to N limitation. To examine factors possibly leading to changes in P supply, we measured pools and transformations in soil P, and developed a long-term mass balance to estimate the co...

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Bibliographic Details
Published in:Geoderma 2014-04, Vol.217-218, p.65-73
Main Authors: Homyak, Peter M., Sickman, James O., Melack, John M.
Format: Article
Language:English
Subjects:
Agronomy. Soil science and plant productions
Alpine ecosystems
Aluminum
Atmospheric P deposition
Biological and medical sciences
Earth sciences
Earth, ocean, space
Exact sciences and technology
Freshwater
Fundamental and applied biological sciences. Psychology
High-elevation lakes
High-elevation soils
Horizon
Iron
Lakes
Parents
Pools
Sequential P fractionation
Soils
Surficial geology
Transformations
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Summary:In high-elevation lakes of the Sierra Nevada (California), increases in P supply have been inferred from shifts in P to N limitation. To examine factors possibly leading to changes in P supply, we measured pools and transformations in soil P, and developed a long-term mass balance to estimate the contribution of parent material weathering to soil P stocks. Common Sierra Nevada soils were found to not be P-deficient and to be retentive of P due to the influence of Fe- and Al-oxides. Total P averaged 867μgPg−1 in the top 10cm of soil (O and A horizons) and 597μgPg−1 in the 10–60cm depth (B horizons), of which 70% in A horizons and 60% in B horizons was freely exchangeable or associated with Fe and Al. Weathering of parent material explained 69% of the P found in soils and lost from the catchment since deglaciation, implying that long-term atmospheric P deposition (0.02kgha−1yr−1) represented the balance of P inputs (31%) during the past 10,000years of soil development. During spring snowmelt ~27% of the total soil P was transferred between organic and inorganic pools; average inorganic P pools decreased by 232μgPg−1, while organic P pools increased by 242μgPg−1. Microbial biomass P was highest during winter and decreased six-fold to a minimum in the fall. Interactions between hydrology and biological processes strongly influence the rate of P transfer from catchment soils to lakes. •High-elevation Sierra Nevada soils have high P content and P retention capacity.•Fe and Al-oxides control P retention in soils.•Weathering of granitic parent material can explain 69 % of the P in soil.•Atmospheric inputs appear to substantially subsidize soil P stocks.
ISSN:0016-7061
1872-6259
DOI:10.1016/j.geoderma.2013.11.003