With all the posts on this machine, perhaps this is pertinent. I have operated a z spray since November and have been amazed at its productivity on spraying apps. We just began granular ferts here last week and I have experienced some difficulty with bridging of fert in the spyker hopper. I visited with spyker a couple of times on solutions. I did install a screen and have tried different types of agitators, but none really helped. The fertilizer would feed through your standard lesco pusher. It soon became evident that the fert contained too much moisture to properly feed especially in humid conditoins. Yes it is a urea based nitrogen fert. No, it is not SCU what I normally use, but that is a different matter that soon will be rectified. Finally, I tried some year-old SCU fert that had been in the back of the shop. It spread beautifully. My supplier now has 8 pallets of fert that could be bought cheap. The hassle has delayed us a week. Hope it can help others avoid the problem.