I'm doing classification for soils have more than 30 % of CaCO3, located in arid and semi arid conditions Could you please give me your opinion if i have a calcic horizon or not?
According to WRB-SR a calcic horizon has more than 15% CaCO3 and more than 5% secondary carbonates. So it seems quite obvious that you have calcic horizons. However, you need to make sure that you have indeed secondary carbonates and not just a calcareous parent material.
I think that the key factor is the detection of secondary carbonates in the soil matrix (if requirements according to thickness and quantity are fulfilled). This can be detected in field by the presence of accumulations in several forms (nodules, pseudo-myceliums, etc) that usually can be observed with a naked eye. The increase in CaCO3 content in an horizon (5%) in relation to an an underlying horizon is also determinant. In some soils it is not so easy, in that cases the micromorphological study by petrographic microscope is required to identify the specific pedofeatures of secondary precipitation of carbonates.