Mineral nitrogen and microbial activity in soils of the Central Bolivian Highland

Aylin Caballero Mamani; Roberto Miranda Casas; Hugo Bosque Sánchez; Justina Condori Mamani

Abstract

The mineral nitrogen content and the microbial activity with different management were evaluated in four seasons of the year in soils of the community of Villa Patarani of the Central Bolivian highland. Six plots of study were identified: plot with tarwi residues; Potato residues; 3 years at rest; 6 years at rest; 7 years in rest and plot with continuous cultivation of quinoa. In each one, soil samples were obtained at three points in triplicate, between 0 and 10 cm depth. The determination of the mineral nitrogen was carried out by reduction - Kjeldahl distillation and subsequent quantification of NO3- + NO2- and NH4 +; Microbial activity was determined through the production of CO2 during microbial respiration in terms of mg C-CO2 • kg^-1 of soil. The results showed that mineral nitrogen was higher in the plots with 3 and 6 years at rest (2.04 and 1.97 mg kg^-1 Soil), evidencing the positive effect of rest on the content of NO3- + NO2- and NH4 +.The periods where there was increase in the mineral nitrogen content were in the months of March, November and January. With respect to microbial activity, there were higher increases in the plots with 6 and 3 years at rest (9.31 and 7.51 mg C-CO2 kg^-1) and a lower value in the plot with continuous quinoa cultivation (5, 20 mg C-CO2 kg^-1) the months where the microbial activity was favored were March and January due to the favorable conditions of humidity and temperature.