With corn production declining in the Southeast this year, effective and efficient irrigation for those who choose to produce the crop is a must. Inefficient irrigation can waste time, energy and, most importantly, money.
And without effective production of corn, profits could be in an even shorter supply.
According to the National Agricultural Statistics Service, Georgia is expected to plant about 260,000 acres of corn in 2006. This would be a 10,000-acre decrease from 2005 when the state reduced its corn crop by about 65,000 acres. The expected decrease in 2006 of about 22 percent of the state's crop from the past two years can be attributed to several factors, including the rising cost of fuel and a decrease in corn prices.
While prices may be beyond farmers' control, profitability begins with smart choices at the beginning of the season, including scheduling for irrigation.
Kerry Harrison, a University of Georgia Extension agricultural engineer who specializes in irrigation, says there are many scheduling methods available to farmers today, and they should choose the one that works best for them.
“There are about as many different methods as there are people these days,” Harrison says. “They all pretty much fit into two approaches: cutting edge and average everyday.”
Harrison says among the “cutting edge” approaches to irrigation scheduling are C-Probes, moisture blocks and tensiometers — or any measuring device that gets into the field and measures soil moisture. He says these devices can be beneficial to someone with a lot of land or even for the small-scale farmer, but they will be expensive for both.
“Any time there is a method that automatically measures soil moisture in the field, it's going to cost $100 to $500 per station,” Harrison says. “That's expensive even if you use only one per field. You can make most of them accessible from your desktop, but at that point you're just adding cost.”
Dewey Lee, a University of Georgia Extension agronomist, says that while soil moisture measuring devices can be expensive, they can be more economical depending on the size of the farming operation.
“I think for someone who needs that automated help on a large scale, it can get expensive, but also more economically feasible,” Lee says. “It just depends on how much help you need.”
In a paper written by Lee and Harrison titled “Scheduling Corn Irrigation,” they explain that the most simple way of scheduling irrigation is to use the check-book method. This method helps keep track of the amount of available water in the field during the most important stages of the corn's life.
They advise growers to use the UGA Evaporation-based Accumulator for Sprinkler-enhanced Yield (EASY) Pan. The pan is a float-based mechanism that shows the grower the root depth of the crop and its holding capacity.
While the method of irrigation is important, it is just as important if not more so for farmers to make sure they get the timing right, says Harrison.
“With irrigation, there is a right time for every crop,” Harrison said. “For corn, that time is around pollination.”
Harrison explains that the lifespan of corn is a lot like the lifespan of a person in terms of how much water it needs at the different life stages. When the corn is young it needs frequent but not much water. He says a common mistake is to waste water early in the season.
The middle stage of the corn's life is when it needs the most water — similar to a teenager, he says.
“You don't feed baby formula to a teenage boy,” Harrison says.
He adds that once the corn becomes mature, the amount of water it requires will decrease and level off. The timing of the water application is more important than the amount of water applied, he says.
A common misconception, he says, is that if the crop requires 1.5 inches of water twice a week, it's okay to apply 3 inches once a week if an application is missed.
“That water would just turn into runoff,” Harrison says. “If that happens, the farmer needs to get back on schedule as soon as possible.”
Lee says growers need to understand their soil as well as their crop when deciding the specifics of irrigation. The soils with the least capacity for holding water will need to be watered more frequently because of their porosity, he says.
Areas like Tifton, Ga., with loamy sand will need moderate intake because of the soils' average permeability, explains Lee. However, with a semi-clay loam, the water will need to be absorbed slower to avoid runoff.