After finishing the watershed delineation, and after creating the HMS schematic in Arcmap, i was trying to include the land use map and soil map in the process, by using the CNgrid preparation by using Analysis tools-Overlay-Union command. But in order to do that the attribute table for both layers must contain specific column headings. Unfortunately I do have only the names of the each feature in the soil layer, so I have to populate the other features on my own. In the soil layer there must be 4 columns:"PctA”, “PctB”, “PctC”, and “PctD”. These columns contain the percentage of each hydrologic soil group (A, B, C, and D) in the soil layer polygons, which I populated with our geologist. But also there are two other columns there are very important in order to do the join of the features of the soil layer, these columns are MUSYM and MUKEY, where MUSYM - is a map unit symbol that should only be used when working with the data from 1 survey. I do not have these data and i dont know to populate them on my own, but without them i can not join the layers. i searched at dataset ESDAC but i dont know which of them to download and what method to use.
MUKEY stands for MapUnit KEY. It is a numeric value (stored as text) that links the mapunit to other tables in the SSURGO database that store mapunit attributes. See p. 70 of the SSURGO Table Column Descriptions.
If the program you are using does not use either of those attributes you could populate the table with your own MUSYM and MUKEY values for each unique soil type.