If I have 8 rural acres how can I get that changed from residential to agricultural?

If you are contemplating this zoning/classification change based on use of the property, your question might have to be answered by the Appraiser's office.  There are several factors that impact the information you need.  I suggest you contact Mr. Paul Null with the Records and Tax Administration office.  You can reach Mr. Null at 913-715-0782 and he will provide the information you need.