If el-moggo is digging in your mulched area or soft soil spots bury a few loaded mouse traps with the mechanism downwards, carefully place so as not to trigger them, then cover with mulch or soil.
When old mate goes to dig or even walks across the ground it will set off the mouse trap which will spring out of the ground (like the jumping jack mine) and scare it off.
As cats do not like confrontation this generally works.
It worked with SWMBOs cat when it was using my vege patch as a dunny (quite entertaining to watch a cat leap feet in the air) it still won't go near the patch even after 5 years.