Emission of CO2 and soil microbial activity in sugarcane management systems

Abstract

Because of the great importance of sugarcane in the Brazilian agricultural sector, this study was developed in order to evaluate the soil CO2 flux and the soil microbial activity in the systems of burned sugarcane and green sugarcane. For this end, three areas were evaluated with different histories of sugarcane management: (1) burned sugarcane BS); (2) green sugarcane for 5 years (GS-5); (3) green sugarcane for 10 years (GS-10), considering that both areas of green sugarcane were converted from a scenario of prior burning before harvest. The soil CO2 flux (FCO2), basal respiration (BR), carbon of the microbial biomass (CMB), metabolic quotient (qCO2) and microbial quotient (qMIC) were evaluated in 30 points in a 100 × 100 m sampling grid, amounting to 1 ha. The results indicated higher FCO2 and CBM in the GS-10 area, and lower in the BS area, whose CO2 emission and microbial activity were higher in summer. The metabolic and microbial quotients showed a greater balance of the soil microbial activity in the area of green sugarcane for 10 years, fostered mainly by the higher amount of mulch on the soil.\r\r\t \r\r\tKey words: Saccharum officinarum, soil respiration, microorganisms, mulch.