JD, I know there's an awful lot of stuff out there that I haven't seen yet. The plastic wrap that I'm familiar with is a clear plastic, and it's perforated so it can "breath". And of course, it wraps around the bale, leaving the ends open. But I've also seen a few bales that used an opaque white plastic wrap that covered the entire bale; ends and all. I haven't seen the machine that did it, but apparently it's what you're talking about because I was told it was baled silage.
Wish I'd had my camera with me last month to make a picture of a silage storage place I saw being filled about 15 miles from here. Last year I noticed a big concrete slab being poured on a tract of land out in the country and wondered why anyone would be building a big warehouse out there. Then they built some high concrete walls on the two long sides. Last month, I was passing by there and the big trucks were hauling in silage and there was one of those big articulated 8 wheeled John Deeres with a front blade up on top, smoothing, leveling, and packing it. I don't think it's quite as big as a football field, although it may be; definitely the biggest "silo" I've ever seen. I was by there a couple of days ago and it's now full and covered with plastic.
Bird