I have a Bourgault 3310 w/ 6450 cart.  I run it with the 591 monitor.  Is there a way for me to use variable rate for fertilizer (granular) with that configuration.  I think they (bourgault)  have a ZRC??  Zone Rate Control box.  I haven't checked with bourgault yet. Not sure if I can run it with the 591 or if I have to  move up to newer model monitor system.   just gonna see if anyone has experience with it.  Started with VR NH3 last spring and liked it but running that thru JD 2600.  

TIA