Yes, this post I found in my travels. CORE77 has the original but Boing Boing posted a link to it, as did Virginia Postrel.
After tossing the idea around a bit, I wondered okay, how would they actually plant it? The planting act on the field could be dangerous. Then I read the comments on the original posting and was relieved to find that the others who came before me had similar questions so I had no further comment.
"More than 100 million land mines kill or injure 26,000 people in 45 countries each year. Today's most popular detection method is poking around with a stick."
What do you think?