Don’t turn off the pivot sprinklers right after harvest.

A local irrigation expert says even in October it is beneficial to continue irrigating fields with pivots, laying some groundwork for next season.

It’s about maintaining a small water reservoir for that field, said Pudge Fagan, the location manager at Agri Industries in Powell. 

Unlike flood irrigation, which runs over the soil, pivots water down onto the crop, pushing the water into the soil. Pivots have an average efficiency of 85% — a 50% increase compared to flood irrigation.

“What we’re trying to do is force that water to keep percolating … down depending on whatever crop it is and how deep that root is going, you want to keep a good available water content in that root zone,” Fagan said.

With a pivot crops are watered more often but with less water.

“As it starts to warm up and the crop starts growing actively, you start putting more water to [the crop],” Fagan said.

In the hottest months, July and August, it’s important to be consistent, especially with alfalfa and hay crops. The crop should not be flooded with water, which could stunt the growth and push oxygen out. 

In order to accommodate various conditions Agri Industries, which has offices in Wyoming, Montana and North Dakota, offers a variety of sprinkler heads and other equipment that can work to the specific location. Sensors, in partnership with Simplot, can also be used that go 3 feet deep into the soil and take in data every 4 inches.

“ A lot of times, you can double the production on the field, you know, depending on your water practices,” Fagan said. 

Around now as the temperature starts to drop the amount of water will roll back, he added. Water will stay in the ditch until the middle of October, and as long as water is available and it’s not too cold for the pipes, watering can still take place. Then in the springtime, when it starts to warm up again, having available water content in the soil means crops like alfalfa have moisture to start off the year. 

The subsurface irrigation is critical for pivots and crops. The water won’t filter through as quickly in the winter time, Fagan said, and when the ground begins to thaw you can actually see a wet spot coming up under the frost.

“When you plant [your crop] you’ve already got some subsurface irrigation that that crop can pull from in the spring before you’re watering, so you’re keeping that, that reservoir charged as much as you can,” Fagan said.