Opuntia ficus-indica chronosequence affects soil carbon mineralization rates

Opuntia ficus-indica, known as cactus pear, is exceptionally well-suited for arid climates, thriving through its crassulacean acid metabolism (CAM) which enhances water use efficiency and enables photosynthesis under drought conditions. This adaptive feature supports both fruit production and use as forage in drought-prone regions such as Africa and South America. This study investigates the impact of orchard age on soil organic carbon (SOC) mineralization across orchards aged 1 to 30 years in Roccapalumba and San Cono, Sicily (Italy). Soil samples from 0- to 15-, 15- to 30-, and 30- to 60-cm layers were incubated at 25°C to measure CO2 emission as a proxy of microbial activity and the breakdown of organic matter. The results demonstrated that SOC mineralization rates, expressed in mg CO2-C kg-1 soil d-1, tended to increase with the age of the orchard. This enhanced mineralization process is the result of soil C accumulation over time, and it is critical for sustaining soil fertility and promoting sustainable agricultural practices in ecosystems where CAM plants are prevalent. The study highlights the importance of understanding SOC dynamics to optimize soil management practices, aiming to maintain productivity and ecological balance in arid agricultural systems. These findings offer a valuable foundation for designing targeted strategies to improve carbon cycling and soil health, ultimately contributing to sustainable land use in regions characterized by water scarcity.