This article (http://scienceline.org/2011/07/lawns-vs-crops-in-the-contine...) is about water usage, but it states that there is more lawn acreage in the US than the 8 top irrigated crops combined.
(Discussed here: https://www.huffingtonpost.com/entry/lawn-largest-crop-ameri...) (original here: http://www.isprs.org/proceedings/XXXVI/8-W27/milesi.pdf)