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Nutrient Status in Alpine Soils of the Colorado Front Range Using the Nitrogen/Phosphorus Ratio Index
Author(s) -
Litaor M. Iggy,
Seastedt T. R.,
Sackett L. C.
Publication year - 2008
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj2006.0434
Subject(s) - nutrient , phosphorus , soil water , nitrogen , chemistry , zoology , agronomy , human fertilization , environmental chemistry , environmental science , biology , soil science , organic chemistry
The suitability of the foliar N/P ratio was evaluated as a predictor of nutrient limitation in an alpine ecosystem of the Colorado Front Range. We hypothesized that foliar N/P ratios are directly correlated with the alpine soil nutrient status. We used a long‐term fertilization experiment conducted in three alpine plant communities, where 48 plots were established consisting of four replicates of control, N, P, and N + P additions. We characterized four extractable P fractions, maximum P sorption capacity, and extractable NO 3 –N and NH 4 –N, measured N and P adsorption fluxes, determined the soil moisture content, and measured the total N and P concentrations in soils and below‐ and aboveground plant material. The fertilized plots exhibited significantly higher nutrient concentrations in above‐ and belowground plant materials and adsorption fluxes of N and P ( P < 0.001 for all additions) than the control plots. The N‐added plots were significantly acidified (<3.8) vs. the control plots (>4.14), which may have partially contributed to increased P flux. A correlation analysis showed that N and P accumulations in aboveground plant material could not be predicted by the traditional extractable N and P tests. Nutrient adsorption flux measurements and especially P showed better correlation with nutrient accumulation in below‐ and aboveground plant material ( r = 0.53 and 0.43, respectively, P < 0.001). This moderate correlation suggested, however, that the N/P ratio index is somewhat limited in providing a definitive answer for the nutrient limitation status of this alpine ecosystem.