Your ancestor named Bernard Dirks immigrated to Adams County, Illinois, in the 1850s where he lived until he died in the 1910s. He’s in 1860-1910 census in that county, buys land there, etc.
Ancestry serves up a naturalization for a Bernard Dirks in Tazewell County, Illinois, in the 1860s–suggesting it’s your guy. Do you assume it’s your guy? Here are some things you should do–in no particular order.
Geography: Determine how far apart Adams and Tazewell Counties are. Locally did it: Is there a naturalization for Bernard Dirks in Adams County, Illinois?
Said so on census: Did the Adams County, Illinois, Bernard Dirks indicate he was naturalized in any extant census record? Is the year relatively consistent with the Tazewell date?
Contemporary dude search: Look at census and other records in Tazewell County around the time the Bernard Dirks naturalized there. Does that name appear in those records–during that time when your guy is in Adams County? That would really suggest there were two dudes in different places with the same (or similar) names.
Just some thoughts.