We bought some fields a few years ago, in some places you could lose your welly (very difficult trying to pull your welly out of the mud while other foot is sinking!)
We dug channels, found some old stone drains, now most of the land is walkable, but still wet in winter and rushes about.
What is interesting is GOOGLE EARTH, on the ground the rushes seems random, but on arial views you can see the lines of rushes, which show where the old drains are.