With all power off, open each electrical box and blow it out with compressed air. Avoid leaving any dust or debris in the box or connections. Seal holes that rodents, snakes or insects may use to gain access to the box. A small application of a long residual action insecticide to the bottom of the box can reduce ant and spider problems in the future. Inspect the function of disconnects and repair or replace faulty equipment. Make sure all connections are tight and all connection surfaces are free of corrosion. Many electrical disconnects or pivot control boxes meet an early demise from an electrified mouse nest explosion in the box.
If you generate your own power, start the engine and bring it up to proper RPMs for the generator. Check the voltage at each pump and pivot in the system. Inspect the grounding wire from terminal to rods. Some irrigated crop contracts have requirements for testing of the grounding system and maximum resistance. Make a list of needed repairs for your electrician to follow-up on and get them started before the traditional over-committed first days of irrigation season.
Pumps run for hours without operator presence, and even small oil or coolant leaks can result in damage. Inspect belts, batteries and recharge system. Look carefully for rodent damage and insect nests that may result in a malfunction later. Inspect pump murphy or safety shut-down systems or install them if you do not have them. Low oil and high temperature shutdowns can avoid burning up your engine.
Many of your neighbors may be concerned that irrigation water use is permanently lowering the water table. Documenting the static water level in your well and surrounding wells before you start pumping each year allows a comparison from beginning to end of pumping season. A late fall reading will show the recovery levels. If you do not have the equipment to measure the static water level of your well, consider an annual well maintenance company inspection or a single visit from a well driller to inspect equipment and measure water levels.
Slowly fill water supply lines allowing air to escape from ends of lines. With the distribution system running furthest from the water source, inspect all the remaining outlets for freeze damage, missing frost plugs and leaks. Compare last year’s records with your start-up reading for pressure and flow.
Many power companies have a demand charge as a factor in your monthly bill. In some cases, these demand charges can be substantial, even a couple hundred dollars for a large motor or pump. These charges are often based on the peak power use over the billing period for a short period of time (15 minutes for example).
Some power providers have off-season plans to avoid service charges over the winter. Knowing when the billing cycle starts and ends allows a producer to schedule start-up and avoid unnecessary charges. It is always good to have the irrigation system ready before planting, but in some cases starting the pump a month or two before it’s needed can result in hundreds of dollars of extra cost.
Remove debris, sand and small stones from rock traps. Clean screens and filters often used in conjunction with end guns and cornering arms. Rock traps are often removed for the winter to prevent freeze damage from water condensation in pipes and accumulating in traps. If rock traps were removed for the winter and bird guards are not put in place, inspect openings for nests.
Start the system up and pressurize it. Look for leaks and bad sprinklers and create a list of units in need of attention. Remember to check risers and other irrigation pipe areas that may need attention. Small leaks can saturate the soil and weaken force blocks used to hold underground pipe end plugs in place. Create a list of pressure and flow meter readings (if available) for each pumping station and pivot point. Knowing the starting pressure can help diagnose in-season irrigation problems later.
With water up to pressure, check sprinkler patterns. This can be easily done on bare earth or when crops are small. You can also use a drone to fly over the pivot to quickly do a check of the sprinkler package and look for leaks. Look for sprinklers that have smaller wetted patterns than others. Plugs, no-turns and non-uniform watering patterns would indicate damage. Check pressure at the pivot point and the last sprinkler and compare to the sprinkler chart; pressure that varies from the chart by more than 10% indicates the need for attention.
Hydro valves are the most common method used to turn off the irrigation water on cornering arms and Z-arms that are in their folded back position. If valves are stuck open, you are grossly overwatering end-rows or other field edges where the arm is not deployed. Valves that are stuck closed will result in under-watering corners of the field. While the machine is running, inspect sprinklers in a corner area with the arm fully deployed to make sure all sprinklers come on and then in an area with the arm fully folded to see if all valves shut off.
Pivots that make partial circles often use stop barricades at the edge of the water area. Check stops for integrity, making sure the height is still appropriate for the machine’s turnoff mechanism. Manually operate the turn-off arms on the pivot to make sure they are functioning. Newer style stop barricades are designed to catch and spin the tire against the barricade, allowing the safety system to shut the pivot down as a backup safety system.