A TOOL TO DEFINE THE TOTAL SOIL RESPIRATION IN A MEDITERRANEAN VINEYARD

The total soil respiration (TSR) is the main component of the global flux of CO2. The knowledge of the spatial and temporal variability of TSR is a key in order to understand the ongoing changes in the global climate. The objective of the research was to assess the dynamics of TSR for a long time in a vineyard of southern Italy. A fixed automatic home-made chamber system was used to measure the TSR along three growing seasons. A portable gas-analyzer (Li-Cor 6400-09) was used to study the TSR spatial variability. A non-invasive geophysical technique (electromagnetic induction - EMI) was applied in order to find a significant relationship between TSR and apparent soil electrical conductivity (ECa). The CO2 rates ranged from 0.78 to 43.7 g CO2 m-2 d-1. TSR increased during the spring while it decreased in 45 to 50% throughout the first half of the summer. The daily evolution of the TSR recorded differences between seasonal periods studied, indicating a clear change in the TSR measured on row and inter-rows positions. The irrigation influenced significantly (P <0.001) TSR that increased about 300% during the following week. Significant correlations were found between the TSR and ECa (R2 ranges from -0.43 to -0.83). Spatialization of TSR to the field scale was performed using linear regression between TSR values and EMI signal. The result allowed a more detailed view of the vineyard soil CO2 emissions that could be available and useful for more precise information on the CO2 emission that is complex and difficult to measure component of the carbon balance in the agro-ecosystem