Farmers using center pivot irrigation should pay special attention this year to make sure the system has plenty of clearance, says Lyndon Kelley, a Purdue and Michigan State Extension specialist.

Plant debris and other obstructions could become entangled in a system’s lateral arms, potentially causing thousands of dollars in damage, Kelley said.

“It is especially important to check for obstructions this year because last year’s excellent growing conditions produced a very tall crop in many fields,” Kelley said. “In a few unfortunate situations, the tall crop and lack of sufficient clearance led to a pivot being flipped or rolled.”

Center pivot irrigation systems typically consist of a central pump tower, also called a pivot, which drives the lateral sprinkler arms in a circular track. The lateral arms are designed to be high enough off the ground to clear any mature plants.

If the arms are caught up in brush and unable to move freely, however, the force of the drive mechanism could put a dangerous amount of stress on the system, Kelley said.

“It’s like revving a car motor when you’re stuck in a ditch,” he said. “The mechanical components are not designed to work that way.”

Most cornfields in the Midwest require about 7 feet of clearance for the lateral arms, although fields with Sudan grass, silage corn and other tall crops could require 9 feet, Kelley said. Most tower legs, used to support the lateral arms, provide about 9 to 10 feet of clearance.

Farmers should also know the topography of their land.

“Hills and valleys can pose problems for center pivot systems,” Kelley said. “Operators should identify any areas that need to be addressed, and if they have questions they should have the pivot supplier map the hilltops and compare that to the tracks of the lateral arms.”

Most irrigation equipment suppliers have products available to adapt center pivot systems for hilly or uneven terrain, Kelley said.

For more information on center pivot systems or other irrigation questions, contact Kelley at 269-467-5511 or kelleyl@anr.msu.edu.