Abstract

CANON-CORTAZAR, Roger Guillermo; AVELLANEDA-TORRES, Lizeth Manuela  and  TORRES-ROJAS, Esperanza. Associated microorganisms to the nitrogen cycle in soils under three systems of use: potato crop, livestock and páramo, in Los Nevados National Natural Park, Colombia. Acta Agron. [online]. 2012, vol.61, n.4, pp.371-379. ISSN 0120-2812.

This study estimated the population density of microorganisms associated with the metabolism of nitrogen (N) in soils with three uses: potato crop, livestock and low intervention zones (high plains or páramo) in the El Bosque district of Los Nevados National Natural Park in Colombia. The following microorganisms were indirectly quantified: amonifiers (AMO), proteolytic (PRO), ammonium oxidizing (BOA), nitrite oxidizing (BON) and denitrifiers (DEN) in soils of three farms located at different altitudes and under two climatic seasons. The non-parametric Kruskal-Wallis test paired with a significance level of P < 0.05 was used to detect statistically significant differences among abundances of functional groups of microorganisms. Then a principal component analysis (PCA) was performed to evaluate the relationships among different variables. The results showed differences among all the groups, with páramo soils having the lowest density of microorganisms in the soil. The PRO microorganisms were the most abundant in all soils, followed by DEN, with a higher density in the páramo ecosystem. The microbial population density was not significantly affected by altitude but showed some differences that did not have a unique behavior pattern. Additionally, differences were seen in the seasons, being higher in the dry season for the PRO, AMO, BOA and BON groups; and in the rainy season for DEN. This study provided knowledge of the relationships between land use and the presence of microorganisms associated with the nitrogen cycle.

Keywords : Ammonium oxidizing; amonifiers; denitrifiers; nitrite oxidizing; proteolytic.

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