Adding to the previous answers: Central pivot irrigation tends to be built in regions where agriculture is limited by water supply, not by land area. Where the

Adding to the previous answers: Central pivot irrigation tends to be built in regions where agriculture is limited by water supply, not by land area. Where the farmer on humid lands ask "how do I work efficiently with my land area", his peer on arid lands asks "how do I work efficiently with my annual water volume". (Edit: and it always ends in tears when the actual question being asked is "how do I get most out of our shared water supply") Where land is the main limitation, you'd most likely not go from square circle packing to hexagonal circle packing, you would get rid of circles altogether. (Wikipedia does have pictures of hexagonally packed, so apparently there exists a level of intermediate land scarcity where the trade-offs work out in favor of hex-packed circles)