Although it seemed to be raining over most of the winter months, the reality is that the early winter received most of the rain, and it tapered off by mid-to-late winter. By spring, the soil profile, while containing more moisture than in several years, was rapidly depleting.
Climate predictions call for a dry May and June. Therefore, irrigation will be needed. The key is knowing exactly when the most moisture is needed for maximum yield and grade.
Know The Peak Need
John P. Beasley, Jr., University of Georgia Extension agronomist, says in the 20-week growing season for peanuts, the critical period for water comes from week 10 to week 17.
“A peanut crop needs 23 inches of water, but almost 19 inches of it are needed in that time frame. Week 10 to week 17 is the time for the highest water requirement in peanuts,” he says.
Beasley notes that rarely do producers receive 23 inches of rainfall during the growing season.
“The closest we came to receiving that much rainfall during the growing season was in 2003,” he says. “Therefore, in most every year we are in a rainfall deficit for peanut production.”
Beasley says the key to growing any crop, peanuts included, is in knowing the water requirement for the crop and when it needs the most moisture. “The peak need for irrigation in corn is just after planting of cotton and peanuts.”
Match The Growth Curve
Beasley says back in the early part of the decade when the states of Georgia, Florida and Alabama were in constant talks about the Flint River and possible restrictions were being bantered about, a group of University of Georgia Extension and research personnel had a meeting at the Stripling Irrigation Park in Camilla, Ga., with the sole purpose of coming up with strategies to reduce water use in peanut production.
“Prior to this, our standard recommendation was simply to apply two inches of water per week. So, we asked the question, ‘What if we just put out an inch and a half per week?’
“What we determined was that producers could put out three-fourths of an inch with the pivot and then come back with the same amount for total of about one and a half inches.
“We adapted the growth stage water curve model to match putting out one and a half inches,” he says. “What we have found out through our research is that we were watering too much early on and then not enough when the crop needed it.”
• Avoid putting too much irrigation on early and not enough when the crop needs it
• The greatest water requirement is from week 10 to week 17
• Whatever the crop, know the water need and peak timing
• It is rare for a peanut crop’s water requirement to be fully met by rainfall
• Use the scheduling method that fits your management style
• Attempting to apply water efficiently will affect the crop in a dry year
Use A Scheduling Method
Other irrigation research projects have looked at using an irrigation scheduling method, such as Irrigator Pro, the computer-based expert system, or the UGA EASY Pan, the low-cost wash tub and float method.
The UGA EASY (Evaporation-based Accumulator for Sprinkler-enhanced Yield) Pan Irrigation Scheduler is designed to provide in-field monitoring of crop water needs in humid areas for a fraction of the management time and cost associated with other irrigation scheduling methods. Irrigator Pro is one of the products and services offered through the USDA-ARS Web site. Other irrigation scheduling methods are available.
Strive For Efficiency
Beasley says the UGA EASY Pan often called for less irrigation events than other scheduling methods.
“It was interesting that even though EASY Pan was triggering less irrigation and less water and the crop did yield less, it came out better economically because of the cost of applying irrigation in that year,” he says.
The scheduling method used depends entirely on the user and their comfort level with the method and calculations.
“As long as you try to water your peanuts efficiently, you will affect production in a dry year,” Beasley says. PG