Peer review

Eighteen laboratories reported the analyses of seven plant tissue referee samples for the elements N, P, K, Ca, Mg, Al, B, Cu, Fe, Mn, Na, and Zn. Agreement among the laboratories was good for the elements N, P, Mn, Mg, K, and Ca. Poor agreement was obtained for the elements B and Cu with only fair agreement for Na, Al, Zn, and Fe. The results from this exchange of samples were not too different from those obtained by others in similar studies. Although the probable sources for the variances were not investigated, failure to specify drying and ashing technique, as well as the lack of plant tissue standards from a reliable source, may have contributed to discrepant analyses in some laboratories. Also, analysts need to carefully evaluate calibration and operating techniques, particularly when emission spectrographs are used to perform plant tissue analyses. Exchange of plant tissue referee samples between laboratories can be of assistance to the analyst when plant tissue standards are not available.

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