Net Ecosystem CO2 Exchange in a Subtropical Oxisol Under Long-Term Tillage Systems.

Agricultural soils can act as a source or sink of CO₂ depending on the management practices adopted. The objective of this research was to evaluate the net ecosystem CO₂ exchange in long-term soil management systems (convetional tillage (CT) and no-till (NT)) over a subtropical Hapludox in southern Brazil. Data were collected by an automatic meteorological station mounted in micrometeorological tower two meters above the ground. Turbulent variables were measured by a three-dimensional sonic anemometer Campbell-3D (wind and temperature components) and by an infrared gas analyzer Licor 7500 (H₂O e CO₂). Eddy covariance method was employed to measure the C-CO₂ exchange that resulted of the interaction between atmosphere and the soybean cropping system. Soil temperature was measured using two sensors (thermopar) installed in the soil and for moisture measurement were used two sensors ECH₂O.