There were lots of circles on the ground. I couldn't figure what they were.
That is how they farm there. The irrigation systems are sprinklers that go in circles. Center pivot irrigation
"
The center-pivot irrigation system is considered to be a highly efficient system which helps conserve water.
Center pivot irrigation typically uses less water compared to many
surface irrigation and
furrow irrigation techniques,
[6] which reduces the expenditure of and conserves water. It also helps to reduce labor costs compared to some ground irrigation techniques, which are often more labor-intensive.
[6] Some ground irrigation techniques involve the digging of channels on the land for the water to flow, whereas the use of center-pivot irrigation can reduce the amount of soil
tillage that occurs and helps to reduce water runoff and soil erosion that can occur with ground irrigation.
[6] Less tillage encourages more organic materials and
crop residue to decompose back into the soil, and reduces soil compaction.
["