It boggles my mind how little people are aware of this kind of practice. The Who even wrote a "joke" song about it in the 70s:

https://youtu.be/_VkVn0A7E6o

Well, I farmed for a year and grew a crop of corn 
That stretched as far as the eye can see 
That's a whole lot of cornflakes 
Near enough to feed New York till 1973

Cultivation is my station and the nation 
Buys my corn from me immediately 
And holding sixty thousand bucks, I watch as dumper trucks 
Tip New York's corn flakes in the sea

~~

Well, my pick and spade are rusty
Because I'm paid on trust 
To leave my square of cornfield bare

Probably to keep from ripping up the top soil during the harvest. Kind of counterintuitive to use less farmland and to produce less when the price is high, but same thing works with oil fields - you get more the slower you pump.