Soil Carbon Dioxide Emissions and Carbon Sequestration with Implementation of Alley Cropping in a Mediterranean Citrus Orchard.

Agroecological ecosystems produce significant carbon dioxide fluxes; however, the equilibrium of their carbon sequestration, as well as emission rates, faces considerable uncertainties. Therefore, sustainable cropping practices represent a unique opportunity for carbon sequestration, compensating greenhouse gas emissions. In this research, we evaluated the short-term effect of different management practices in alleys (tillage, no tillage, alley cropping with and on soil properties, carbon sequestration, and CO emissions in a grapefruit orchard under semiarid climate). For two years every four months, soil sampling campaigns were performed, soil CO emissions were measured, and rhizosphere soils were sampled at the end of the experimental period. The results show that alley cropping with and contributed to improve soil fertility, increasing soil organic carbon (SOC), total nitrogen, cation exchange capacity, and nutrients. The CO emission rates followed the soil temperature/moisture pattern. Tillage did not contribute to higher overall CO emissions, and there were no decreased SOC contents. In contrast, alley crops increased CO emission rates, especially ; however, the bigger root system and biomass of contributed to soil carbon sequestration at a greater rate than . Therefore, is positioned as a better option than to be used as an alley crop, although long-term monitoring is required to evaluate if the reported short-term benefits are maintained over time.