Pivot Performance: As we think about and look at data from 2023 and at costs for 2024, something that has come up in a few conversations is pivot performance. Water covers a multitude of problems. The lack of moisture much of the past 2-3 years, the number of hail and windstorms, and the number of pivots and/or nozzles that were replaced are all factors to consider as you view yield maps and imagery. For example, in the rush of getting new pivots up and going, the wrong nozzles were placed on the wrong spans in some situations. It’s easy to do and can make a big difference in water output and distribution. It’s also easy to check to make sure nozzles are correct on the pivot by driving alongside of it and checking it with what the sprinkler package design says. Would encourage anyone who replaced pivots/sprinkler packages to add this to your checklist before irrigation season next year.

Another field I was checking fairly often in 2023 showed too much variability of plants in the field; imagery showed a problem too. I thought there was something wrong with the water output but was told that couldn’t be a problem. Turns out the wrong sprinkler package was put on that pivot after checking into it further; it can easily happen when several pivots are being replaced for the same farmers who get hit by these storms. Everyone is doing their best during these times of disaster events to keep ag going, yet mistakes can happen. I also think about how often a nozzle that was damaged gets replaced with whatever is handy vs. the correct nozzle, so that’s another thing to think about before irrigation next season.

My colleague, Bruno Lena in Platte County, received a Nebraska Soybean Board grant to work locally with growers on understanding their uniformity of water application. He worked with three growers and provided an excellent summary of what they did and their case study findings in the following CropWatch article: https://go.unl.edu/yfb8. The economics are also provided; it’s well worth a read.

Essentially he worked with growers on ‘catch a can’ tests where cups are mounted on stakes like electric fence posts and distributed evenly along a pivot. He and a team of colleagues worked together to collect the information. “Initially, pivots 1, 2 and 3 exhibited uniformity of water application (UWA) values of 78%, 59% and 23% with the old nozzles, as these pivots had received minimal maintenance attention since their initial installation. Growers noted that these pivots were 21, 34 and 38 years old, still equipped with the original nozzle package. Following the replacement of nozzles, all pivots demonstrated improvements. UWA increased to 92%, 90%, and 74% for pivots 1, 2, and 3, respectively. While pivots 1 and 2 met the manufacturer’s recommendation of at least 90% UWA, pivot 3 still fell short of the recommended values. Upon discussing this with the grower of pivot 3, it was revealed that the primary reason for the suboptimal UWA was the pumping capacity.”

Once the new sprinkler packages were installed, another thing Bruno and his team found were inconsistencies between the selected irrigation rate at the panel and the actual irrigation rate measured by the cups. The measured irrigation depth deviated from the depth selected at the pivot panel. One pivot was underapplying water by 0.19” and another was overapplying by nearly 0.38” each circle.

A father/son operation in York County had built their own catch a can system after working with Dr. Jim Specht and me on a project in 2022. They used it to test nozzle output on different pivots in 2023. On one pivot, they were aiming for 0.75” per circle yet the output in the cups was only 0.40” on average. That was a big realization to be underapplying by 0.35″/circle, especially in a year like 2023. They slowed the pivot down to get the application where it needed to be, and the father mentioned how grateful he was for doing that test. In a recent conversation, he mentioned it was a 30 year old pivot with an upgraded drive system (new center drives and gear boxes two years ago) that led to the gear ratios being different than the original. That was something they didn’t account for when using percentages on the computer printout, so another consideration. With many area pivots being completely new or upgraded in various ways the past few years, I mention all these examples for awareness and consideration as all these details can make a difference in pivot performance as you look at 2023 data and head into the 2024 season.