I want to let my dog crap in a soccer field
That may not be legal. Why would you do that with your dog in a soccer field?
I was thinking about allowing my dog to use the soccer fields to do their business.
Dogs can't help where they go but as their owner you are expected to control your pet. You cannot let them do it wherever, you will have to pay a fine in some places.
So I have to control my dog's progress? I can't even enjoy a dog's company?
You can always enjoy your dog's company, but you need to do it legally and not doing something that will cause harm to people, such as making him poo in a soccer field as people will run around in there and they will step on the poo and probably be injured. I suggest you clean up after your dog and not let him poo in any place that's inappropriate.