I have a feeling this wouldn’t work in Germany, although you can apparently bury your cat in the garden there, if the garden belongs to you.
The Natural Death Centre, a charity for natural burials, provides useful advice on the practicalities of grave digging on its website: “If you are digging a grave yourself, you need to be careful and have help. If you are fit and enthusiastic, it should take about three hours work to dig a four foot deep grave.
“Try and shore up the first two feet of the grave so that it is supported when the mourners stand around it, and work steadily so that you don’t strain yourself. You might want to take a bucket to stand on so that you can get out of the grave at the end of a tiring day!”