Soil carbon dioxide efflux in conilon coffee ( Coffea canephora   Pierre ex A. Froehner) plantations in different phenological phases in tropical climate in Brazil

The agricultural sector is considered an important source of greenhouse gases, in which the coffee crop has an important contribution, participating in the dynamics of soil C and CO₂ emissions. In this way, the aim of this study was to analyze and quantify CO₂ emissions in different phenological phases in soil cultivated with conilon coffee (Coffea canephora Pierre ex A. Froehner), and compare it with CO₂ flow in forest and pasture area. The experiment was conducted in the Experimental Area of the Federal Institute of Espírito Santo, Southeastern Brazil, in an experimental plot of 0.5 ha cultivated with conilon Vitória coffee clones. The quantification of soil CO₂ flux was performed between July 2016 and June 2017, this period comprising all the seasons of the year, using in two rounds of ratings (day and night), with five replicates each. For comparison purposes, another measurement of the CO₂ stream was conducted in June 2017 with an evaluation period of 24 h. The highest CO₂ emission occurred during the harvest phases of the fruit (206.7 mg CO₂ m^-2 h^-1). The lowest daily CO₂ flow records were observed in the rest and flowering phases with values of 82.1 and 83.6 CO₂ mg m^-2 h^-1, respectively. The CO₂ emission from the forest was higher than the emissions that occurred in the area planted with conilon coffee and pasture, during dry season.