Using a Nitrate Specific Ion Electrode to Determine Stalk Nitrate–Nitrogen Concentration

Authors

Wallace Wilhelm, University of Nebraska-LincolnFollow
S.L. Arnold, University of Nebraska-LincolnFollow
James S. Schepers, University of Nebraska-LincolnFollow

Date of this Version

1-1-2000

Comments

Published in Agron. J. 92:186–189 (2000). January-February 2000. Permission to use.

Abstract

The end-of-season stalk NO₃ test has been used to determine N sufficiency in corn (Zea mays L.). Nitrate concentration is commonly determined with flow-injection analysis (FIA), which is accurate but uses hazardous chemicals and is time-consuming. Use of a simpler method of NO₃ determination, such as the NO₃ specific ion electrode (SIE), may save time and costs, and reduce hazards. The objective of this study was to compare estimates of stalk NO₃ concentration by FIA and NO₃ SIE. For FIA, NO₃ was extracted with 2 M KCl, and the extract was filtered before analysis. For SIE, NO₃ was extracted with 0.04M (NH₄)₂SO₄, and the extract was analyzed without filtration. The slope of the linear regression between concentrations estimated by SIE and FIA did not differ from 1.0. Use of the NO₃ SIE, compared with FIA, reduces costs, sample processing, and use of hazardous chemicals.