Carbon Dioxide Emissions in Agricultural Systems in the Brazilian Savanna

The objectives of this work were to evaluate the CO2 emission potential of an Oxisol under integrated crop-livestock and no-tillage systems in the Brasilian Savanna; and to analyze the impact of soil temperature and soil moisture as factors that regulate the seasonality and the emission of C-CO2 in these systems. Field-scale study was carried out at Fazenda Brejinho, in Pedro Afonso-TO, under Oxisol. The production systems studied were integrated crop-livestock and no-tillage under cropped with soybean and corn. The amount of carbon (C) released from the soil in the form of CO2 (C-CO2) was evaluated using cylindrical chambers installed in the field with a vial containing sodium hydroxide to collect CO2 released from the soil (soil emission) in an interval of 15 hours. Five evaluations were conducted over crops growing season, started in 01/26 through 06/16/2015. Data were tested to analysis of variance and the means were compared with Duncan test at 5%. The emission of C-CO2 differed between treatments in all evaluation periods. On average, the temperature ranged from 26.5 to 27.7 °C, the soil moisture ranged from 12.2 to 15.7% and the C-CO2 emission ranged from 87.4 to 119.9 mg m-2 h-1. Temperature, soil moisture and the production systems contributed to the emission and seasonality of carbon dioxide emissions. The integrated crop-livestock cropped with soybean/corn rotation was the system that had the lowest carbon dioxide emission.