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Checklist aims to keep irrigation systems running

YuraWhite/Getty images Irrigation pivot watering a field
KEEP IT RUNNING: Irrigation systems are increasingly more complicated, making maintenance more important. The American Society of Agricultural and Biological Engineers has come up with a preliminary set of checklists for growers.
Whether you're using center-pivot or linear-move sprinkler systems, this series of checklists can help keep them working.

One of the first slides Sandeep Bhatti shows during his talk at the Irrigation Show is a Colorado satellite image that's pivot-filled. Bhatti is a graduate student at the University of Nebraska-Lincoln, and he presented a new article at the 6th Decennial National Irrigation Symposium focused on keeping pivot and linear-move systems moving.

The decennial is held by the American Society of Agricultural and Biological Engineers every 10 years, in conjunction with the Irrigation Association Irrigation Show, held recently in San Diego. Bhatti says the paper was developed when the ASABE NRES-241 sprinkler irrigation committee noted a need for this information. "This is a preliminary list we're presenting, but it has been divided into specific times and tasks," he says. "This is designed for new irrigators, but it can be a reminder to more experienced irrigators."

The article's authors include representatives from California State University; Washington State University; the University of Nebraska-Lincoln; USDA Natural Resources Conservation Service, Portland, Ore., and MJ Consulting, Owasso, Okla.

The list starts with the baseline of information to have available then breaks down other tasks by relevant time period — daily, weekly, annual (end and beginning of the season) — and even drive-by tasks. It's a listing you can use on your farm, or modify to your specific needs:

Information to be readily available
1. Design sprinkler pressure at the pivot.
2. Design flow rate.
3. Table of gross application depths and hours to apply for various percent timer settings.
4. Variable rate irrigation information for that system.
5. Allocation and/or water permit limit.

Daily, for center pivots with telemetry
1. Is system communicating properly and regularly?
2. Does system start and stop on command?
3. Is the system pressure at the designated pressure, or higher or lower?
4. Is the pivot location where it’s expected?
5. Is the end-gun state as expected?
6. Is aux ports state as expected?
7. Is the pivot as expected for the applied water depth?
8. Are field sensors reporting and do data make sense?
9. Status of the water application for the season compared to allocation and water permit. Do adjustments need to be made?

Drive-by items: These are checks you can make from the pickup on a regular basis.
1. Are all sprinklers operating? Are there any plugged nozzles?
2. Observe the water spray pattern of each sprinkler on a calm, nonwindy day to visually assess the pressure and flow rate of each sprinkler.
3. If the irrigation system is equipped with moving parts, such as rotators or spinners, are those parts moving properly?
4. Is the end gun operating correctly over the angles as per the sprinkler chart?
5. Is the end gun spraying onto roads or other areas outside of the crop area?
6. Is there surface runoff (most likely under the last span)? Is water ponding in low spots? This can be due to leaks. If runoff is everywhere, consider speeding the pivot up (applying less water per pass).
7. Is there any visual observation of nonuniform water application areas?
8. Are there any water-stressed areas in the field? When checking system in the midafternoon on sunny days, are the crops showing any water stress, such as corn leaves “rolling” or other wilting symptoms?

Weekly items
1. If the irrigation resource is surface water and a filter is used, check the filters to make sure pressure loss is in an acceptable range.
2. If there is a flowmeter, is the weekly flow rate close to the expected value? For instance, if 1.5 inches of water is expected to be applied in one week for a 150-acre field, the flowmeter should register a difference of 1.5 inches times 150 acres times 27,154 gallons per (acre-inch), equaling 6,109,650 gallons in that one-week time period.
3. If the flow rate or well drawdown changes during the season, update the percent timer on the panel based on the current well flow rate(s). Does the flow rate require a change in sprinkler nozzles?
4a. If using aerial imagery to assess uniformity issues, if a pattern of rings is observed in the field, it could possibly indicate potential nozzle or leak issues.
4b. If pattern of wheel spoke(s) is observed, it may occur at light application depths, due to low pressure setting in the panel is incorrect, if the pump is surging, or if the irrigation schedule results in consistent daytime watering of one part of the field.

Annual items, start of season
1. Locate the current sprinkler chart.
2. If you have a flowmeter, does the flow rate match the sprinkler chart?
3. If it is a part-circle or wiper pivot, are the bumper bars in place and functional?
4. Has the pivot-point bearing been greased?
5. With the power off (be sure it’s really off), have an electrician check for loose connections (terminal screws) or loose cord grips in the control panel and tower boxes. Do contactors show signs of arcing?
6. Are the electrical grounding conductors solidly connected? (both to-the-ground leads and terminals, and the power supply ground wire) Clean or tighten as required.
7. Check condition and pressure of all tires. Check wheel lug nut torque and wheel alignment if the pivot is newly installed.
8. Check for water leaks at tower joints, goosenecks, and at sprinkler and hose couplings.
9. Does the operating pressure match the design pressure (from the sprinkler chart)?
10. Check the oil level in the gear boxes (will need a wrench to open fill plug). Is there water in the oil? If so, drain the old oil into a collector and fill with new oil.
11. Are the drive-shaft safety shields in place?
12. During center-pivot operation, check for gearbox noise indicating wear or problems.
13. Is the filter for the hydraulic tubes for hydro-valve actuators clean?
14. Does the pivot alignment look straight when it is operating?
15. Check for rodent damage to wiring by checking if there are visual marks on the wires, and if all electrical communications and commands are working as expected.
16. Walk the entire system while it is operating, and check wheel track depth.
17. Is it time to replace the sprinkler nozzles, sprinklers or regulators? Issues to look for are: a) indications of non-uniformity in the field, which may be related to sprinkler operation; b) Higher flow rates and lower pressures than expected. Replacement is usually recommended every five to 10 years, depending on water quality.

Annual items, end of season
1. Prepare water use report.
2. Record hours of operation for the season. Do they seem reasonable, based on the weather conditions?
3. Will you need to budget for winter maintenance?
4. Was the system flushed? Are the sand traps clean?
5. Is the pivot and connections to the well completely drained of water?
6. Is the power off?

Every five years
1. Do a pumping plant performance audit.
2. Consider replacing the sprinkler package. Does the package need redesigning or updating?
3. Compare installed nozzles to sprinkler chart.
4. Are pressure regulators working as expected or do they need to be replaced?
5. Do pressure gauges and flowmeters need replacement?
6. Change the gearbox oil at the interval recommended by the manufacturer.

These checklists are new, and subject to some changes. During the presentation, some engineers suggested moving some five-year items — such as pressure regulator checks — to annual items. The list is still under review, but it offers farmers a solid starting point for improving irrigation system management.

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