How much is actually used for ranch vs personal use?

28 acres were actually used for the ranch. 

For this: "28 acres have been classified by the tax office as agricultural land."

In my State, anything 10 acres and over is considered Agricultural. So, your two parcels individually qualify.

You also already described that legally this is Split.

And you didn't tell us What you are working on entering, so that there is some perspective to any other splits.

More details always help.

They sold the entire property in 2019 and I am trying to separate the sales amount into what is personal residence and what is the sale of the farm business. They did not ever deduct any of the expenses of their personal residence. 

They had to apply to the tax office years ago to have ten of the acres that were on the legal description with the house to have them qualified for the AG exemption.

As IRS would see it, the county classification and $5 would buy you a cup of coffee at Starbucks except they're probably closed.  Yes, you should "split it as 28 acres for business and then 1 acre and the house as residence as it is used."