Major Procedural Discrepancies in Soil Extracted Nitrate Levels and Nitrogen Isotopic Values |
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| Authors: | Charles W Lindau Roy F Spalding |
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| Institution: | Assistant Professor and Professor, respectively, Conservation and Survey Division, Institute of Agriculture and Natural Resources, University of Nebraska, Lincoln, Nebraska 68588–0517. |
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| Abstract: | Preliminary vadose zone nitrate extraction experiments have revealed the extractant (2N KCl) volume affects the determination of nitrate and its nitrogen isotope ratio. In five cores, extractable NO3-N concentrations increased an average of 1.7 times after the soil-to-extractant ratio was increased from 1:1 to 1:10. An increased extractant volume resulted in a large positive shift of stable nitrogen values (δ15N), which averaged +6.2%. An underestimation of available NO3-N for leaching and transport through the vadose zone and a biased source interpretation from the δ15N values probably would occur if a procedure which leads to incomplete extraction of nitrate is used. |
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