Answer

There is a religious feel to the image ‘processional stooping through the turf recurs mindlessly as autumn’ there is no thought given to the process, it is merely a natural and habitual event, like autumn following summer. The fear of a ‘famine god’ means that they kneel in reverence to the ‘altar of the sod’. They worship the ground and the potatoes that come from it as without it they would starve, just as people worship god to help them through difficult times.