Nitrógeno mineral y actividad microbiana en suelos del Altiplano Central Boliviano
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Abstract
Se evaluó el contenido de nitrógeno mineral y la actividad microbiana con diferente manejo en cuatro épocas del año en suelos de la comunidad de Villa Patarani del Altiplano Central Boliviano. Se identificaron seis parcelas de estudio: parcela con residuos de tarwi; residuos de papa; 3 años en descanso; 6 años en descanso; 7 años en descanso y parcela con cultivo continuo de quinua. En cada una de ellas se obtuvieron muestras de suelo en tres puntos por triplicado, entre 0 y 10 cm de profundidad. La determinación del nitrógeno mineral se realizó por reducción - destilación Kjeldahl y posterior cuantificación del NO3- + NO2- y NH4+; la actividad microbiana se determinó a través de la producción de CO2 durante la respiración microbiana en términos de mg C-CO2•kg-1 de suelo. Los resultados obtenidos indicaron que el nitrógeno mineral fue más alto en las parcelas con 3 y 6 años en descanso (2,04 y 1,97 mg kg-1 Suelo) evidenciándose el efecto positivo del descanso sobre el contenido de NO3- + NO2- y NH4+. Las épocas donde hubo incremento en el contenido de nitrógeno mineral fueron en los meses de Marzo, Noviembre y Enero. Respecto a la actividad microbiana, se registraron mayores incrementos en las parcelas con 6 y 3 años en descanso (9,31 y7,51 mg C-CO2 kg-1) y un menor valor en la parcela con cultivo continuo de quinua (5,20 mg C-CO2kg-1) los meses donde la actividad microbiana fue favorecida fueron Marzo y Enero debido a las condiciones favorable de humedad y temperatura.
We evaluated the effect of management (incorporating crop remains and fallow plots) and time of year on mineral nitrogen content and microbial activity (N min and AM) in soils of the community Patarani Central Bolivian highland (3400-4000 m). We identified six study plots: a plot with lupine residues, a plot with potato waste), a three-year fallow plot, a six years fallow plot, a seven years fallow plot) and a plot with continuously cultivated quinoa. In each plot, three points were sampled in triplicate, between 0 and 10 cm deep. The determination of mineral N was performed by reduction and distillation in Kjeldahl and the subsequent quantification of NO3-+ NO2-and NH4+. Microbial activity was determined by CO2 production during microbial respiration in terms of mg C-CO2 kg-1. The results indicated that the mineral N was higher in plots with three and six years fallow (2.04 and 1.97 mg•kg-1 soil) evidencing the positive effect of fallow on the NO3-+ NO2- and NH4+ soil content The months when an increase in the mineral N content was observed were March, November and January. Regarding microbial activity, increase was also higher in plots with 6 and 3 years fallow (9.31 and 7.51 mg C-CO2•kg-1) and a lower value on the plot with continuous cultivation of quinoa (5.20 mg C-CO2•kg-1) the months when microbial activity was favored were March and January due to the favorable conditions of humidity and temperature.
We evaluated the effect of management (incorporating crop remains and fallow plots) and time of year on mineral nitrogen content and microbial activity (N min and AM) in soils of the community Patarani Central Bolivian highland (3400-4000 m). We identified six study plots: a plot with lupine residues, a plot with potato waste), a three-year fallow plot, a six years fallow plot, a seven years fallow plot) and a plot with continuously cultivated quinoa. In each plot, three points were sampled in triplicate, between 0 and 10 cm deep. The determination of mineral N was performed by reduction and distillation in Kjeldahl and the subsequent quantification of NO3-+ NO2-and NH4+. Microbial activity was determined by CO2 production during microbial respiration in terms of mg C-CO2 kg-1. The results indicated that the mineral N was higher in plots with three and six years fallow (2.04 and 1.97 mg•kg-1 soil) evidencing the positive effect of fallow on the NO3-+ NO2- and NH4+ soil content The months when an increase in the mineral N content was observed were March, November and January. Regarding microbial activity, increase was also higher in plots with 6 and 3 years fallow (9.31 and 7.51 mg C-CO2•kg-1) and a lower value on the plot with continuous cultivation of quinoa (5.20 mg C-CO2•kg-1) the months when microbial activity was favored were March and January due to the favorable conditions of humidity and temperature.
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Vol. 1, No. 1