The goal of all centre pivot irrigation systems is to deliver irrigation water. If the initial field reconnaissance has taken place correctly, the field elevation change, flow rate, pump outlet pressure and pumping water level all combine to match up with sprinkler requirements. Life is good.
But what should be done with systems that have been in the field for several years? I've found systems with sprinklers missing, and systems where tower boots were spewing water down to the wheel track. There are several aspects of this that can have a very detrimental impact on water application uniformity.
1. Leaking systems
If extra water is coming out of the sprinkler coupler or there is a leaky boot, the pressure delivered to every other sprinkler on the system is less than the sprinkler design chart requires. So what looks to be affecting a small area of the field is actually affecting the whole area. Sprinklers cost less than $50, and replacing a boot won't break the bank either.