As far as I know in KY there is no minimum acreage to be considered a small farm but you need to have at least $1,000 of gross sales per calendar year.
You can call our local Farm Service Agency office at 859-624-1981 ext 2 to register your farm with USDA and they will assign you a farm serial number. This will allow you to be eligible for certain programs if they become available. Sometimes assistance with federal disaster declarations for farms.
Locally, we have a cost share program called CAIP that is administered by our Conservation District 859-624-1981 ext 3. Their office is in same building as Farm Service Agency at 1024 Ival James Blvd Richmond 40475. Behind Ag Credit on the Richmond Bypass. There are options for various types of farm improvement grants. They are 50/50 up to $3000 per producer. You can spend $6000 up front and get reimbursed for the $3000. Bulls, heifers, fence, forage, hay storage, equipment are among the options. Signups will be this April. Contact Lisa Smith for more information.
Not sure about grants for work on farms.