A calorimetric analysis of soil treated with effective microorganisms

Abstract

Effective microorganisms or EM is a consortium of beneficial microorganisms (primarily photosyntheticand lactic acid bacteria, yeast, actinomycetes, and fermenting fungi) that can be applied as inoculants toincrease the microbial diversity of soil. Two fields of sugar cane in the province of Tucumán, Argentinawere treated with either EM containing brewery fermentation tank residual yeast (YS) or just EM (NYS).The outcome was 1000 kg Ha−1 less of sugar cane harvested from YS field. The aim of this work was toanalyze both soils to find out if calorimetry could assess the negative effect of yeast. Mass specific thermalpower?time curves were obtained during 100 or more h of measurement. Once a day, a vial containingNaOH solution was introduced into the calorimetric ampoule to determine CO2 evolution. A plot of logSMB (soil microbial biomass) as a function of log p gave a similar relation as previously reported for thosesamples that showed an energy expenditure of 16?22 J cm−3 CO2 respired. Thus, soil microbial biomasscould be determined during microbial growth. Results showed that yeast suppressed the activity of partof the soil microorganisms. Also, soil microbial activity increased with time in NYS due to successiveapplications of EM.