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  • 1
    In: REVISTA TERRA LATINOAMERICANA, Sociedad Mexicana de la Ciencia del Suelo A.C., Vol. 37, No. 3 ( 2019-07-15), p. 273-
    Abstract: The Mexican regulation NMX-EC-17025-IMNC-2006, establishes that laboratories must have quality control procedures to monitor the validity of tests and calibrations, such monitoring must be planned and reviewed with: a) the regular use of certif ied reference materials or internal quality control of secondary references; b) participation in inter-laboratory comparisons or a prof iciency testing program; c) the repetition of tests or calibrations using the same method or different methods; d) the repetition of the test or the calibration of determined objects; e) the correlation of results for different characteristics of a reference material certif ied by MRC. The quality evaluation of results from the eight laboratories of the Laboratory Network for Analysis, Use, Conservation and Management of Soil (REDLABS) included the elements of sections a), b), c), and d) in order to verify the hypothesis that laboratories emit repeatable, reproducible and unbiased results. In our study, elemental analyzers of different brands were used to measure the total carbon of soil. A certif ied reference material was included in the Inter-comparison Practice. Repeatability and reproducibility of the carbon analyzes were evaluated with samples from the inter-comparison practice; the precision of analyzes from each laboratory was qualif ied with MRC. The results obtained indicate that the laboratories show repeatability in their analyzes with no statistical differences, i.e. reproducibility is detected by inter-comparison. The data issued by the laboratories were unbiased according to their evaluation with certif ied reference material.
    Type of Medium: Online Resource
    ISSN: 2395-8030
    Language: Unknown
    Publisher: Sociedad Mexicana de la Ciencia del Suelo A.C.
    Publication Date: 2019
    detail.hit.zdb_id: 2406278-9
    SSG: 7,36
    Location Call Number Limitation Availability
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  • 2
    In: REVISTA TERRA LATINOAMERICANA, Sociedad Mexicana de la Ciencia del Suelo A.C., Vol. 37, No. 3 ( 2019-07-15), p. 261-
    Abstract: Pine (Pinus sp.) sawdust has been used as a growing medium for the cultivation of vegetables and ornamentals. In the present work the objective was to assess the immobilization or retention of N, P, K, and Ca in pine sawdust as the main substrate component by applying Steiner nutrient solution at different concentrations (20, 30 and 40 meq L-1). We used uncomposted sawdust, alone or in mixtures (70/30, v/v) with volcanic tuff of different particle sizes (fine ≤ 3 mm, medium 3-6 mm, and coarse 6-12 mm). For two months, leachate was collected daily, and every 10 days, the average concentrations of N, P, K, and Ca, as well as pH and electrical conductivity (EC) were measured. The effect of the interaction substrate × nutrient solution concentration on N, P, K and Ca in the leached water was observed. These nutrients increased in concentration in the leachate water in accord with the nutrient solution concentration and as the diameter of volcanic tuff particles diminished. Irrigation with 20 meq L-1 (2 dS m-1) concentration of nutrient solution reduced the concentration of N, P, K, and Ca in leached water below its concentration in the supplied nutrient solution, while irrigation with 30 or 40 meq L-1 (2 or 4 dS m-1) resulted in similar concentration in leached water up to 20 or 30 dat, but at 40 dat, concentration of these nutrients in the leached water was higher. Immobilization of N and P, K, and Ca retention in the sawdust substrate occurred during the first 40 ddt, related to an increase in pH (up to 8.6), a decrease in EC (until 0.5 dS m-1) and low concentrations of N, P, K, and Ca in the leached water.
    Type of Medium: Online Resource
    ISSN: 2395-8030
    Language: Unknown
    Publisher: Sociedad Mexicana de la Ciencia del Suelo A.C.
    Publication Date: 2019
    detail.hit.zdb_id: 2406278-9
    SSG: 7,36
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
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