I don't know about that. When we lived on the farm, we always spread it with a pitchfork. That took long enough. I can't imagine having to spread it with a butter knife. We'd never get done in time for dinner.
You're waiting too long! I spread two truckloads by pitchfork this fall, but the mix of straw and time made it pitchable. When fresh you can use a butter knife, but not for gardens. That is when it is toxic and corrosive. They try to make us sandwiches out of it.