Around here, every couple of years, a barn goes up in flames because of spontaneous combustion. It's quite a task to extinguish a smoldering bale. It's hard to get water inside, which is where the fire is. The choice is to either let them burn or unroll them and hose them down.

Regarding using it to dispose of human waste, I'm positive that a round bale can handle far more than a good dose of human waste -- feces or urine. A round bale holds enough carbon to contain the smell and reduce a dead adult dairy cow to nothing more than the large bones in 30 to 40 days. <http://www.uaex.edu/Other_Areas/publications/PDF/FSA-1044.pdf>

Regarding the comment about someone digging into a round bale using a knife, I'm skeptical. The hay is tightly packed and all the stalks or stems are oriented in the same general direction. Cutting, or digging, your way into the heart of a round bale -- IMHO -- would be impossible.

My 21-year-old son laughed when I asked if he'd try to dig in to create a survival shelter. His advice: "Pull off a few layers to use as a blanket, then get on the downwind side." That would be far easier. And MUCH faster.

He also noted that if round bales (or any bales, or haystacks, for that matter) are around, a house or barn is not too far away.

Maybe the person lost in a blizzard dug into a haystack -- far less densely packed than a round bale.