Bret, had a renter years ago who wrapped poly on his round bales. Lost a bunch of it in the fields. Took me years to pick it all up. Note the neighbor has a bunch of it scattered in his feed lot, and bunches wrapped around the beater of his spreader.
We work awfully hard to keep the sisal out of the enviornment here, but some may escape in the feeding operation. Some may sneak in on rebaled broken bales in the fields. Constant vigalence. Don't need any tragedies around here. Don't need it wrapped in bearings on machinery or lawn mowers. Fortunately, sisal does biodegrade - when you least want it to!