Not necessarily true- coroprate ag practices in places like central valley California and Arizona/southern NM that grow year round do "flush" their fields via excessive flood irrigation once a year in between crop rotations to flush out built-up salts/spent pesticides and herbicides, just like people in cannabis growing (for better or worse). It's required for certain salt- intolerant crops, mainly due to unsustainable ag practices, soil mining, and the need to fert the shit out of crops every few months....