Nebraska Extension: irrigation system evaluation
Steve Melvin, Nebraska extension educator, shares advice of when and how to conduct an irrigation system evaluation.
The perfect time to evaluate the irrigation system is when we are using it, so it can be evaluated what is working and what is not. It is difficult to start the system in the winter to check it out. The water level in the wells are pumped down, which makes it easier to see how they perform during the whole season.
The key area to evaluate is the design pressure. The design pressure can be found in the sprinkler chart. Also, a new copy can be obtained from your dealer. If the pressure is not right, the system cannot be working correctly. If the pressure was correct when the sprinkler package was new, but it is too high now, check for plugged nozzles or restrictions in the pipeline. If the pressure is too low, it indicates too much water is exiting the pivot or a problem with the pump output. A flow meter is a helpful tool in this situation, because it will tell if there is more or less water flowing through the system than is needed.
A sprinkler package should be visually evaluated every couple of weeks.
The best way to do this is to look at the pivot when it is running in the morning or evening when the sun can be seen gleaming off the water. The pattern should look very even with less water close to the pivot point and increasing toward the outer end. Leaks or plugged sprinklers can usually be seen.
Another good way to evaluate the sprinkler package is to look for non-uniform circular patterns in the crop. They can often be seen in summertime aerial images or if bad enough, from the combine cab at harvest.
