That is not hay it's straw and that it's not a haystack and that is not a hay stacker. Those are straw bales.
There's so much specialization within the farming industry, tons of machines that can do one thing, and one thing only. I imagine being an engineer in that business is really fun!
But the real question is:
How much hay could a haystack stacker stack if a haystacker could stack hay?
I initially read the caption as “haystacker stacker”, and was waiting for the first stacker to be lifted by an even larger machine and stacked.
And my friends couldn’t even rerack properly in college