Know what the waterflow is before you try to change it.

Knowing the land first is I believe the first principle of design.  Those who worked this farm before me saw water collecting in the field after rain events as a problem rather than a solution. They tried to make drainage to the south to the road drainage.  These did not work well and dried out the clay field so that grass would stop growing in the heat of summer.  Observation while mowing the field with scythe was that there was a large Z shaped natural flow from one wet spot to the next That kept the whole field hydrated.  So it has been a prosses of filling in ditches and putting in 4 inch culverts where I want to maintain a level pathway. and I am gradually getting back to the original pattern of when the glacier left and the water level dropped to sea level. I don't mind that the field is shaped in triangles instead of squares.