In this study, the effects of zinc (Zn) and humic acid (HA) applications on soils (12 Aridisol soil samples) formed on limestone and marl parent materials, which are very common in Türkiye, were tested by incubation, adsorption, and greenhouse experiments. Adsorption experiments were carried out using the batch sorption technique, and the Langmuir and Freundlich isotherm parameters were calculated. In the incubation, soils were incubated with control, HA, Zn, and HA+Zn, and the DTPA-Zn was tested in five different periods (1, 7, 15, 30, and 90th days). Maize was grown for eight weeks in pots in the greenhouse. The maximum Zn adsorption for all soils ranged between 3333 and 6250 mg kg-1 in marl soils and 1042 and 5263 mg kg-1 in limestone soils, which decreased to ranges between 2631 and 5555 mg kg-1 in marl soils and 1052 and 5000 mg kg-1 in limestone soils with HA application, respectively. The desorption rate (%) of adsorbed Zn increased as the initial Zn concentra-tion increased in all soil series formed on marl (smectite clay mineral) and limestone (kaolin-ite clay mineral) parent materials. The effects of humic acid and Zn application on the fresh and dry weights of maize were found to be statistically significant at the 5% level for marl and limestone parent material. Humic acid application increased the fresh weight of maize compared with that of the control. The highest available Zn was determined in Başkuyu series (0.79 mg kg-1) formed on marl parent material, while the lowest available Zn was obtained in Saraççeşme series (0.60 mg kg-1) formed on limestone parent material. In the greenhouse, HA increased the fresh weight of maize in soils formed on both parent materi-als by 0.4 and 19.6%, respectively, compared to the control. Zn fertilization with HA further increased the fresh and dry yields, with 12 mg kg-1 performing better. Smax (maximum Zn adsorption of the soil) parameters of soils were negatively correlated with EC, Pav, Kav, or-ganic matter, silt, clay, total N, and cation exchange capacity (CEC) of the samples. Although HA alone increases the availability of Zn in plants, HA + Zn applications should be applied together to obtain higher yields.