Finally, among the adopted mulches, the HV was the most effective for increasing the tomato yield in both experimental years, but the effect of HV mulching on soil quality and microbial functional diversity, similarly to LP, was strongly affected by the climatic conditions. According to previous studies, the Monthly Aridity Index may be a useful tool for agronomists and soil scientists which represents an interesting new approach for studying on soil quality and processes, although Al can also be used for weather-crop production model building under specific agricultural practices such as mulching. ln this study, the Low Monthly Aridity Index in 2012 may accelerated LP mulch decomposition, causing a depletion of tomato yield as final effect. Microbial activity was also affected by climatic conditions, probably because precipitation influenced soil extractable C availability which promoted microbial functional diversity as shown by the increase in Shannon’s Index