And it can be used upfield though so the groundwater carries the dirt into organic fields. Many of these "rules" are written like physics stops at some arbitrary line. To be honest "organic" is a bit of a joke in the farming community , as their fields tend to "hug" coventional fields to prevent a fungi overgrowth .
And we all know agrarian traders who get certified "organic" stuff from countries were any seal or certificate is just a bribe away.
All plants i know get fungi, especially late in the dry and ripen stage.It reduces yield, is toxic and carcinogenic. So fungizides are deployed during the plants lifetime to keep the contamination in check and the product healthwise unproblematic. Organic farming does not have that option. So the fungi rate of some organic farms approaches a total loss. So they hug conventional farms to get the fungizide floatsome for a better result.
And we all know agrarian traders who get certified "organic" stuff from countries were any seal or certificate is just a bribe away.