Quantifying Soil Uptake of Oxygen As a Predictor of Carbon Dioxide Emission.

In the soil system, there should be a linkage between the consumption of oxygen and the production of carbon dioxide (CO2), due to aerobic microbial mineralization of organic matter. This movement of gases occurs both by diffusive and advective transport mechanisms. Fundamentally, these gas fluxes will be in opposite directions, due to the source of oxygen in the atmosphere and the soil source of CO2, but are both impacted by soil properties and agricultural management decisions. The objective of this study is to correlate the emission of CO2 (FCO2) with the uptake of oxygen (FO2) across contrasting agricultural management scenarios. Two contrasting sites of sugar cane residue management were selected near Sao Paulo, Brazil for this purpose. Two areas were selected that possess similar soil materials, but different management strategies: (1) mechanized harvest with leaving 100 % of residue on the soil surface [green harvesting – G] compared to (2) surface burning of the residues (B). The FCO2 was larger from the B treatment during this study, with an average increase of 30% compared to the green harvest field and inversely correlated to the O2 (r= -0,35). On the other hand, the largest observed FO2 occurs in the G management. Additionally, the FO2 was inversely correlated with soil moisture across both management treatments. These observations will also be compared to laboratory incubation data across different soil types examining the temperature, moisture, and sensitivity of FO2 as a co-variant for FCO2.