Hello,
Andy from OSM's Data Working Group here.  As a frequent flyer-over of and occasional visitor to centre-pivot irrigation infrastructure, I'd definitely have thought that it was better described in OSM terms as "farmland" rather than "meadow".  Looking at an example such as https://www.openstreetmap.org/#map=15/43.3265/-120.5190 it's pretty clear that whatever crop that was isn't just meadow grass - crop rows and tramlines are clearly visible.
If you think that that is wrong, I'd suggest discussing it on the community forum (perhaps at https://community.openstreetmap.org/c/help-and-support/tagging/71 ).
Best Regards,
Andy