MO Statute 137.016.  "Agricultural and horticultural property", all real property used for agricultural purposes and devoted primarily to the raising and harvesting of crops; to the feeding, breeding and management of livestock which shall include breeding, showing, and boarding of horses; to dairying, or to any other combination thereof; and buildings and structures customarily associated with farming, agricultural, and horticultural uses. Agricultural and horticultural property shall also include land devoted to and qualifying for payments or other compensation under a soil conservation or agricultural assistance program under an agreement with an agency of the federal government...."

The deadline to file for an agricultural classification is March 1st.