Effect of temperature on soil microbial biomass and its metabolic quotient in situ under different tillage systems |
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| Authors: | Roberto Alvarez Oscar J Santanatoglia Roberto Garcîa |
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| Institution: | (1) Laboratorio de Radioisótopos, Facultad de Agronomía, Universidad de Buenos Aires, Av. San Martín 4453 (1417), Buenos Aires, Argentina;(2) Estación Experimental Agropecuaria Pergamino-INTA, C.C. 22 Pergamino, Argentina |
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| Abstract: | Variations in the microbial biomass and the in situ metabolic quotient (qCO2) due to climatic conditions were determined in a typical soil from the Argentine Rolling Pampa. Microbial C was evaluated by fumigation-incubation and qCO2 was calculated using soil respiration in the field. An inverse relationship between microbial C and soil temperature was fitted to a model (r
2=0.90, P=0.01). No significant association with the soil water content was detected because the soil was generally near field capacity and thus water availability did not limited microbial growth and activity. Values of qCO2 increased (r
2=0.89, P=0.01) as the result of metabolic activatìon, likely induced by a higher maintenance energy requirement at high temperatures. The highest values of qCO2 were obtained when microbial C was the lowest, which was attributed to self consumption of microbial C in the presence of high temperatures. Consequently, microbial C was generally higher (P=0.05) in winter than in summer. Therefore, when microbial C is used as an index of soil biological activity, the influence of temperature should be taken into account. |
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| Keywords: | Microbial biomass Metabolic quotient Seasonal variation Climatic conditions Soil respiration Tillage systems |
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