my dog digs

Question
I have a 6yr old golden that we have had for a year and a half. We live on a farm so is lots to do and plenty of exercise, we take him on runs  and to the pond to swim ,play fetch,groom him, and really do spend a lot of time with him. For the past 2 weeks we have kept him tied up at night as he has been digging our lawn up during the night . I really think he is after toads so my husband and I relocated 7 of then and the 8th I accidentally ran over.He is loose all day and enjoys the farm life but at night he turns into "the excavator".The last time Jake was untied during the night he dug 18 different spots on the lawn. Again he has a whole farm to dig up, but he likes the lawn. So did I at one time.I have heard of giving him his own dig spot and read up on it but I really dont feel that would be a solution to him .I personally think that would give him a green light to just go berserk. He is a very submissive dog, he was  neutered when we got him, but just not the sharpest knife i the drawer.We can also never catch him doing it.My husband wants to put dog shoes on him at night thinking he wont be able to get a foot hold on the lawn.Is there any thing  you could recommend us do.The thought of my lawn destroyed again just kills me. Thank you.

Answer
I'm not sure what you could do side from putting a fence round that part.  

Although I did hear that if the dog has made a hole, use the dog's own feces (MUST be his/her OWN feces), and put it in the hole. Dogs hate the smell of their own feces and will never dig in that spot again. This is particularly useful if your dog keeps digging in the same spots over and over.

Another couple of things I have heard, but can't vouch for are.

Roll out the hose and fit a sprinkler on the end. When the dog goes to investigate the area, turn on the sprinkler. In this way the sprinkler is telling the dog off, and not you. The added bonus of letting the sprinkler do the work for you is that many dogs will learn not to dig whilst you are present but can dig away happily when you are away from home. The sprinkler causes the dog to think that the actual garden is chastising him and does not realise that you were involved at the tap end!

I also know that dogs hate the smell of citronella.