I have a very small (2-3 inches wide and 1 inch deep) puddle in my pasture that is blowing bubbles. I can stick my finger in it and feel the air coming up from beneath.
I first noticed this puddle on January 24 and it's still constantly bubbling. I had a larger (maybe a foot across) puddle that I noticed on January 12 that constantly bubbled until January 19. I dug down about three feet and scooped out most of the water. At the base, air was coming through a small opening from beneath.
The larger one has stopped bubbling, but the little one is still going strong. I guess I am concerned about what is beneath and why it's exhaling through these holes.
I'm glad you reached out, it can be troubling to see a bubbling puddle! Our area has had a huge increase in rain this fall, more than we've had for a few years. It's hard to say what exactly is going on underground, but channels can open up, change, or dry up. It is very hard to trace unless there is a map available of tile drains in the area that is bubbling. This can also happen with septic system discharge drain fields.
I would recommend calling your local Soil & Water Conservation District to see if they have a field drain map for your property on file. SWCDs designed a lot of the tiled drain fields from the 1940s until about 1995 when they got out of the tile drain business.
I'm afraid there isn't too much available unless it is a tile area that has been mapped previously. There is also some risk of a small or even large sinkhole. Remedies are challenging to design but tile drains are still a possible solution if none are there.
Your local SWCD should have more information for you and you can find your local district in the SWCD directory (PDF).