Using a Nitrate Specific Ion Electrode to Determine Stalk Nitrate–Nitrogen Concentration
2000
Wilhelm, Wallace W. | Arnold, S. L. | Schepers, James S.
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 0.04 M (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.
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