Typically I read folks put down 30 actual pounds of fertilizer per acre after first cut - going into second cut.
To simplify this discussion, if the rate were 46 actual pounds, and urea 46-0-0 were used - you would need to put down 100 pounds per acre to achieve 46 actual pounds of nitrogen applied.
I was talking to our coop about this and he made it sound darn near impossible to dial back their buggies or trucks to a rate of 100 lbs per acre of 46-0-0 to achieve 46 actual pounds. So I looked at my new Kubota spreader and the settings for 100 lbs bulk fertilizer are near the lower limit - so much so that they recommend blocking off 2 of the 3 outlets to allow the 3rd outlet to be opened further and prevent clogging.
So I'm curious - what fertilizer you are using on second cutting hay, i.e. 46-0-0, how many actual pounds you're putting down in bulk, i.e. 100 lbs 46-0-0 to achieve 46 actual pounds of fertilizer AND how do you back your fertilizer spread setting down or if it will even go this low without clogging. What is your MPH crossing the field when fertilizing. Our limit is 4.3 MPH due to our irregular/lumpy fields.