Why do pigs root up soil?

Their sensitive nose is as important to pigs as hands are to people. The instinctual drive to use it to root the ground is a deeply ingrained behavior. Reasons include:

• to explore the environment

• to search for food;

• for comfort.

Pigs find food such as grubs, roots, and rich essential minerals below the soil surface. But even if you feed a pig a perfectly nutritional diet, they'll still dig.

Rooting isn't a learned behavior.

Instead, it's what scientists term a behavioral need, which is defined as: “A behavior governed by internal stimuli where, if prevented for a prolonged period, can affect the welfare of the animal.”

Stop a pig from rooting and foraging, and you may see OCD-type behaviors, such as vacuum chewing (chewing repeatedly with nothing in the mouth), and tail biting/mutilation, a common observation on commercial pig farms.