manpower

The tonnage and formula seems to indicate a food mix for animals. It could also mean the producing baby milk or . . .

The manpower will also depend on the split between mechanical and observing work.

Are the workers lazy or not?

please give more detail!

This is fairly easy. We were taught this at primary school (many years ago) and the basic formula is this:-

A man and a half can dig a hole and a half in a day and a half (need to ignore overtime and 360° excavators).

Or have I misunderstood the question?

Experience has taught me that a team of men digging a trench with picks and shovels can move no more than 30 cuic yards of hard-packed clay in one day. Surprisingly, it does not matter how many men one uses- 5, 10. You can have two teams working from either end. Still, 30 cubic yards is the limit. I haven't figured this one out yet, but I suspect if they move 30 yards in 4 hours, they stop working...

Union rule. It's in the book.