The Nitrogen-15 Abundance in a Wide Variety of Soils1
- Georgia Shearer,
- Daniel H. Kohl and
- Sen-Hsiung Chien2
One hundred thirty-nine soil samples from 20 states were analyzed for 15N abundance. Soil characteristics and environmental conditions at the sampling sites varied widely. The total N of surface soil samples had a mean δ15N value (per mill 15N excess) slightly but significantly higher than the mean value for soils collected from deeper layers, although the relationship between δ15N and soil depth was not consistent from location to location. Differences among mean δ15N values for the total N of soil samples collected from cropland, pasture, uncultivated land (with native herbs), and forest were not striking. There was no systematic effect of variation in the rate of application of N fertilizer on the δ15N of the total N of soils. The mean δ15N value of surface soils, with respect to atmospheric N, was +9.22 and the standard deviation was 2.10 δ15N units. The range within which 90% of the samples fell was +5.1 to +12.3 δ15N units. Less than half of the variation among the soils in δ15N of the total N could be accounted for by differences in environmental variables or soil characteristics.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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