Irrigation will help to capture corn yield potential only if everything else is done right, including applying nitrogen, potash and phosphorus and controlling nematodes.
“You had better control nematodes because they naturally affect the roots, and roots are trying to absorb the water. If you don’t have good nematode control, then the water isn’t doing you much good. And, if you don’t have enough nutrition early on, or if you have an uneven plant stand, it’s affecting yield,” said Dewey Lee, University of Georgia Cooperative Extension small grains agronomist.
“As the space increases and flexes between each seed that you plant, you lose yield potential because of the shading effect, competition and other factors. I’m talking about capturing as much yield as we possibly can. I’m not just talking about 200 bushels, but 250, 275, 300 and more. That’s what water can do for us. If you do everything else right, then that’s what water can do for you.”
Weed control is equally important, adds Lee. Many times, using Roundup and atrazine is too easy.
“But why would you want to put herbicide over a plant that’s big enough to intercept the herbicide? It won’t get to the target weed. So managing all of these other factors is part of the concept of successful irrigation.”
Technology today allows farmers to inject nitrogen and fungicides through a center pivot, says Lee, which can save time and be more efficient.
“Your system can be fertilizing or applying a fungicide for you while you’re doing something else. It’s a multi-tasking tool that doesn’t just apply water. We can inject it so that we’re partitioning nitrogen maybe every 10 to 14 days,” he said.
Keeping records is very important in irrigating, he says. “Every time you do something on your farm, write it down. It’ll help you to resolve any problems because everything you do will affect that plant. Keeping records not only helps in looking backwards but also in looking forward.”
Always stay in front of the curve when it comes to irrigating corn, says Lee.
The simple checkbook method has proven effective for Georgia growers, he says. “It’s simple – just deposit the rainfall and irrigation and subtract the plant needs. If you stay ahead, the subsoil will never dry out. With the checkbook method, we’ve been able to closely approximate 100 percent of the water use of that crop. Even in a very dry year, we can closely approximate the need with the checkbook method.”