Abstract

CABALLERO MAMANI, Aylin; MIRANDA CASAS, Roberto; BOSQUE SANCHEZ, Hugo  and  CONDORI MAMANI, Justina. Nitrogen and mineral soil microbial activity in the central highlands boliviano. RIIARn [online]. 2014, vol.1, n.1, pp.65-72. ISSN 2409-1618.

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.

Keywords : organicwaste; mineral nitrogen; microbial activity and effect of management.

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