There are many natural resources generated in cities that are not being used. Inflorescences litter produced by trees in cities can have great potential for use and little is known about the nutritional contributions and chemical composition they could have as soil improvers. The objective of this study was to evaluate the nutritional properties and chemical composition of inflorescence litter of two tree species commonly used in urban landscaping, Jacaranda (Jacaranda mimosifolia) and Jabin (Piscidia piscipula), and mixtures of inflorescence litter material with Andosol type soil. Soil was mixed with inflorescence litter material in different proportions and after an incubation period of 69 days. Changes in nutrient concentrations and chemical composition of substrates were recorded using infrared spectroscopy. It was found that the physical state of the matter and its transformation dynamics differ according to the litter material of the inflorescence and the proportion of mixtures; each species reacts differently to the availability, immobilization or sequestration of elements such as C, N, P, K, Na, Ca, Mn, Mg, Zn and Cu. Microbial capacity intrinsically contained in substrates could partly explain these results, changing the structural and chemical composition, and the physical state of the matter in substrates. The use of inflorescence litter to fertilize or improve soil can be an innovative but still unexplored technique, and a viable line of research to take advantage of a sustainable natural resource that is generally wasted in urban areas.