Certified GKH Gardening Expert
Without knowing your area and climate zone, it would be hard to pinpoint what the actual pest is. This can range from gophers, to moles, deer, hogs. Have you noticed any animals in that area? If they spend much time there, than they are more than likely the cause. You can deter a large number of pests by boiling sliced hot peppers in water for 10 to 20 minutes. Strain this off, and pour the water in the area after the water cools down. This will deter most pests.