Abstract

LOPEZ CHOQUE, Marco Antonio; LOPEZ MAMANI, Miguel Angel  and  YUJRA TICONA, Elizabeth. Evaluation of quality parameters for the determination of total nitrogen in soils. RIIARn [online]. 2023, vol.10, n.1, pp.37-43. ISSN 2409-1618.  https://doi.org/10.53287/tuov3244ge80j.

Nitrogen is an indispensable element for crop nutrition, but it is rarely found in sufficient quantities in the soil to satisfy crop needs; therefore, its adequate determination will establish the amount of nitrogen in the soil and the fertilization programs. The objective of this research work was to evaluate the quality parameters of the Kjeldahl method for the determination of total nitrogen in soils, thus establishing whether the method is suitable for this analysis. The determination of total nitrogen was based on the Kjendahl method, which basically has three stages: digestion, which consists of breaking all the nitrogen bonds in the soil sample and converting all the organically bound nitrogen into ammonium ions. The next stage is distillation where the ammonium ions are converted to ammonia by the addition of an alkali. The last stage is titration which consists of using boric acid as an absorbent solution. The variables were evaluated according to the different quality parameters of an analytical method according to international standard NB-ISO/IEC 17025:2017, these include linearity, limits of detection and quantification, accuracy, precision and uncertainty. The results obtained for total nitrogen, obtained in the laboratory of the Faculty of Agronomy comply with the quality parameters such as linearity, accuracy, precision, thus complying with the Bolivian standard NB-ISO/IEC 17025:2017.

Keywords : total nitrogen; soils; Kjendahl; nitrogen validation; bolivian standard NB-ISO/IEC 17025:2017.

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