It's a term coined and used by one person apparently:

Then, we had reader Erik Sherwood explain it thusly:
“Alan Fountain (my favorite EPSN3 Bundesliga commentator) likes to use this term quite a bit (e.g. to describe the tackling of Schalke’s Papadopolous), but as far as I can tell, it’s a usage unique to him. From context, I take it to mean that the foul was so obvious and/or rough that you’d only expect to see its like committed by a rural rube playing for his village club (which uses the local cow pasture for a pitch, one imagines), not by such subtle, urbane, and expensive players as FC Bayern and all the other Bundesliga clubs field.”
So, an agricultural foul is apparently one that is rough and ungraceful, in the style of someone who would work on a farm, or of a low-budget game that took place on a farm.