Soil respiration in a traditional olive grove in the southeast of Spain

<p>Olive groves occupy a large area in the Mediterranean and their management has repercussions on the carbon cycle in this region. &#160;Weed suppression is the most common management in this crop, but its implications for soil respiration (R_soil) are not well estimated due to the lack in continuous R_soil measurements. In this research we present a full year of R_soil in an irrigated olive grove in which a glyphosate-based herbicide was applied to prevent spontaneous weeds (conventional management). For that, an automatic multi-chamber R_soil system was used (LI-8100 + LI-8150 with 6 chambers, Li-Cor). In addition, soil temperature (T_soil) and soil water content (SWC) were measured next to each chamber. To study the influence of olive trees on R_soil, 3 chambers were placed near the olive trunk and another 3 in the middle of the alleys.</p> <p>Results show seasonal and spatial variability, with higher R_soil in warm months and lower R_soil in cold months. Also, R_soil near the trunk was always larger than in the alleys. The spatial difference increased in the cold months. Diurnal variability was observed with higher R_soil as the soil temperature increased in the alleys, but this was not observed near the trunks. Under the canopy, a decrease in the R_soil is observed as the VPD increases, suggesting a major contribution of autotrophic respiration under the canopy. In addition, there is no positive and negative relationship with temperature and SWC under the canopy, while in the alleys, a strong hysteresis occurs in some periods. Finally, rain events were followed by R_soil peaks. However, low intensity and short duration rain pulses did not manifest on the ground under the olive canopy, so interception is inhibiting this process in part of the agrosystem.</p> <p>This work was supported by the projects PID2020-117825GB-C21 & PID2020-117825GB-C22 (INTEGRATYON3), B-RNM-60-UGR20 (OLEAGEIs) and P18-RT-3629 (ICAERSA) including European Union ERDF funds.</p>