Squirrels, gophers and rats

These are all pests I suspect to be frequenting my garden.  I'm not sure if I have squirrels or gophers or both, but there is definitely a tunneling mammal swiping my root crops.  So today I spent a back breaking afternoon in the garden burying the bottom 12'' of my fence.  Hopefully this will at least deter them.  One fellow gardener said that he had buried his 2 ft and the little boogers still mananged to get in.  I should at least win against the rats.  They live in the brush under the cactus right next to the back half of my plot.  I think they used to slip under the fence, but hopefully burying it helped. Unless they can climb. Or fit through the holes.. meh.