Start Off Irrigation Season With System Inspections and Repairs

As planting nears the end crop producers need to start preparing forirrigation season. If you ignore irrigation equipment until the first really hot dry day you often end up cutting corners and taking risks as you desperately try to get that first irrigation water to fly.

Here are a few suggestions of system inspection and repair areas to concentrate on:

Check and test all control and power boxes. Check and test all control and power boxes. With all power off, open each electric 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 insect 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 problem in the future. Inspect disconnects function 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.

Turn on power supply, using proper safety protocol. If you generate your own power start the engine and bring it up to proper RPMs for the generator. Check 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 him started before the traditional over committed first days of irrigation season.

Service pump engines and inspect all fluid levels. Pumps run for hours without operator presence, 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 shut downs can avoid burning up your engine

Measure static water levels in wells. 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. 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 well driller to inspect equipment and measure water levels.

Start the well or pump. 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.

Rock traps, screens and filters. 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 pipe and accumulating in trap. If rock traps are removed for the winter and bird guards are not put in place inspect openings for nests.

System leaks and bad sprinklers. Start the system up and pressurize it. Look for leaks and bad sprinklers Creating a list 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 (if available) readings for each pumping station and pivot point. Knowing the starting pressure can help diagnose in-season irrigation problems later.

Check sprinkler patterns. With water up to pressure, check sprinkler patterns. This can be easily done on bare earth or when crops are small. Look for sprinklers that have smaller wetted patterns than others. Plugs, no-turns, and watering patterns would indicate damage. Check pressure at pivot point and the last sprinkler and compare to the sprinkler chart, pressure that varies from chart by more than 10% indicates need for attention.

Cornering arm hydro valves. Hydro valves are the most common method to turn off the irrigation water on cornering arm and Z arms that are in their folded back position. If valves are stuck open you are grossly overwatering end-rows or other field edge where arm is not deployed. Valves that are stuck closed will result in underwater corners of field. While the machine is running, inspect sprinklers in a corner area with the arm fully deployed to make sure all sprinkler come on and in an area with the arm fully folded to see if all valves shut off.

End gun adjustments. Make sure you are covering every foot of planted ground possible, or are you watering areas that are not cropped. Fine adjustments now can improve coverage area or keep you out of trouble if irrigation water ends up where it should not be. Avoid going overboard, higher surface and ground water level in the spring can give a little bigger coverage area now that they will late summer.

Check irrigation tires. Check air pressure in each pivot tire. Refill to 20 pounds or recommended level note tires less than 5 pounds, and return a week later to check to see if they leaked. Expect tires to lose two or 3 pounds pressure each year if not re-aired annually.

Service center drive and final drives on pivots. Gearboxes should be checked annually. First drain condensation water from the bottom of the box and then refill with recommended gear lube.

Tree trimming and control brush. Check fence row height compared to pivot overhangs and cut or spray to eliminate damage to the center pivot. Ohio Extensions Brush controls bulletin Relative Effectiveness of Herbicides Commonly Used to Control Woody Vegetation is an excellent resource.

Inspect bridge crossings and wheel paths through rough and low areas. Wheel tracks will only deepen as the season progresses. Identify potential problem areas now to allow time to build-up, fill, level and permanently seed problem areas. In some situations larger tires or track system may need to be added to allow the pivot to float over wet spots.

Chemigation valve and fertigation pump power supply. Many producers are investigating chemigation/ fertigation as an option. Adding the equipment now make it a far more viable option in future. Make sure there is a functional chemigation valve on each water supply feeding into the system. Install an interlocked injection pump power source. This will operate only when the irrigation water pump is on avoiding undiluted fertilizer from ever going into the irrigation system. For a diesel engine this may be as simple as running the injection pump from a v-belt off of the engine shaft.

Stop barricades. Pivots that make partial circles often use stop barricades at the edge of the water area. Check stops for integrity, making sure that the height is still appropriate for the machines turnoffs mechanism. Manually operate the turn off arms on the pivot to make sure that they are functioning. Newer style stop barricades are designed to catch and spin he tire against the barricade allowing the safety system to shut the pivot down as a backup safety system. 

Source: Lyndon Kelley, Michigan State University Extension