As with every county you will want to call and check to verify what you are looking at online is, indeed what the actual requirements are per the appraisal district's mouth. The appraisal district may change chief appraiser like what recently happened in Waller County a few years back, and the rules for qualifying for an Ag Exemption may change year-to-year and especially vary county-to-county. Most appraisal districts will ask that you apply for your Ag-Exemption the year you start keeping bees, knowing it takes 5 years to obtain the exemption. The districts may as you to apply for the exemption in order to "get denied" but during that process the county obtains official records from you the landowner and inputs these documents into their system. This is key, should requirements for the Ag-Exemption change during the 5 year period or the district gets a new chief appraiser who interprets the rules differently than the previous chief appraiser and make changes to degree of intensity requirement. The degree of intensity is applied to all agriculture exemptions, this number determined by the appraisal district, states how many cows you need in a pasture, how much cotton planted in a field, and how many bee hives needed to qualify for the exemption.
Please follow the link below on page 12 for the degree of intensity and below.
"Bee/Honey – This operation involves the placing of hives in order for the honeybee to produce honeycomb. This honeycomb is processed into pure honey food product for human consumption. The hives are placed in groups in an open pasture. A minimum of six (6) mainframe hives to be placed on the minimum five (5) acres. A minimum of twelve (12) mainframe hives to be placed on the maximum (20) acres."