The formation of cracks in clay soils is a physical process with important agricultural repercussions. The specific case occupying us refers to a dryland olive grove (Olea europaea) grown on a vertisol in the countryside of Córdoba (Spain). For two consecutive years, rates of 20 Mg ha-1 of composted sewage sludge have been applied on this land to attempt to improve the physical and chemical properties of the soil. This study proposes a method for the measurement of cracks in clay soil during a desiccation period in trays. The measurement of the cracked area generated in each treatment (20 Mg ha-1 of compost and control) throughout the time, is done on digital photographs, previously orthorectified. The area of cracks generated after a desiccation process decreased by 7% in clay soils amended with composted sewage sludge. Additionally, the soil shrinkage characteristic curve (SSCC) can be obtained.