That’s what they look like, at least:
A Jefferson Grid commenter has a theory about those brown and green swirls:
[In contour cultivation] there are these berms that help to prevent runoff and erosion of topsoil into the gullies during heavy rains. This allows for farming on more sloped areas. This section of land was possibly in CRP earlier and has now been converted to production.
The USDA’s Conservation Reserve Program—or CRP—pays farmers to stop using certain plots of land. NPR’s Dan Charles explains:
Farmers offer to enroll their land in the CRP. It has to be land where crops previously grew. If the USDA accepts the offer, the farmer gets paid a fee, roughly equivalent to the rental value of the land, to stop growing crops on it. The USDA gives priority to land where halting cultivation offers environmental benefits: Less erosion of soil, runoff into streams, or valuable habitat for wildlife.
(See all Orbital Views here)