[Wheat] "Yes, with "intensive" agriculture- lots of irrigation and fertilizers."
No, those figures were from Gene Logsdon's book Small-Scale Grain Raising which was written for small-property owners and home gardeners. The author advocates animal manures, green manures, etc. Wheat is a dryland crop, not requiring much irrigation. Winter wheat is sown in the fall (in milder areas), sprouts, makes a little show of green when the rains come, goes dormant, then sprouts multiple stems for each plant (called stooling) and starts growing again when the weather warms up a bit in spring, and is harvested in midsummer, often without ever being irrigated.
Spring wheats, planted in spring in colder areas, is planted in spring for a late summer harvest. This may take some irrigation, but not as much as many other edibles. And nowhere near as much as many ornamentals.
Sue