Abstract

Ion-selective electrodes (ISEs) are simple tools used for rapid measurement of nitratenitrogen (NO3-N) and potassium (K) concentrations in plant sap. With the developmentof best management practices (BMPs), interest exists in using ISEs for soil leachate andsoil and fertilizer solutions. Nitrate N and K concentrations in the 0 to 10,000 mg L-1ISE working range were measured in diluted solutions of common salts to assess ionicinterference of calcium (Ca2+), ammonium (NH4+), chloride (Cl-), and sulfate (SO42-).The effects of meter (replication) were unexpectedly significant in one out of threeranges for NO3-N and K (P values of 0.50, 0.72, and 0.01 for NO3-N and 0.99, 0.01,and 0.74 for K, for the 0-100, 100-1,000 and 1,000-10,000 mg L-1 ranges, respectively).The responses of calculated NO3-N and K concentrations to measured NO3-Nand K concentrations were linear, but slopes ranged from 0.85 to 1.54, from 0.24 to2.72, and from 0.93 to 5.48 for NO3-N and from 0.80 to 1.01, from 0.71 to 1.39, andfrom 0.93 to 2.21 for K for the 0-100, 100-1,000, and 1,000-10,000 mg L-1 measuringranges, respectively. All slopes were significantly different from zero, and several weresignificantly different from each other and the 1:1 line. Pairwise slope comparisonsconducted with covariance analysis showed that SO42- alone interfered with NO3-Nmeasurements at concentrations ranging from 34 to 171 mg L-1, which was less thanthe manufacturer's information, and by its presence in combination with K+, NH4 +,Ca2+, and Cl- within the medium and high concentration ranges. Potassium measurementswere not subject to interference from the ions tested for all three concentrationranges. These results highlight the importance of using quality assurance / quality control(QA/QC) samples in the set of unknown samples to detect inacceptable departurefrom linearity in routine analysis. The increase in measurement variability from onerange to the next showed the importance of keeping measurements within a single concentrationrange by using dilutions. Hence, ISEs may be used for field measurements ofNO3-N and K concentrations in soil leachate as well as soil and nutrient solutions andare therefore a practical BMP tool. However, ISEs should not be used as substitutes forthe laboratory methods when official measurements are needed.

Autore Pugliese

• Gonnella Maria

Tutti gli autori

• Di Gioia F.; Simonne E.H.; Gonnella M.; Santamaria P.; Gazula A.; Sheppard Z.

Titolo volume/Rivista

Communications in soil science and plant analysis

Anno di pubblicazione

2010

ISSN

0010-3624

ISBN

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Numero di citazioni Wos

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Settori ERC

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Codici ASJC

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