Georgia peanut farmers can save money, conserve water and produce higher yields using a new irrigation scheduling recommendation, according to Wesley Porter, University of Georgia Cooperative Extension irrigation specialist.

The original “checkbook method,” which has producers watering a field a specific amount each week, advises farmers that the total water requirement for peanuts over the course of the growing season is 23 inches. After four years of research at UGA’s C.M. Stripling Irrigation Research Park, Porter has revised those recommendations down to 18 inches.

“After multiple years of research, we observed that the old method was recommending too much water, but the new recommendation is better adjusted to the current varieties and environment,” he said.

Through this research, Porter saw that the original checkbook method, an evapotranspiration average based on historical data, didn’t produce the highest yields. He feared that the crop was being overwatered because, when compared to other more conservative methods, it typically produced lower yields.

Porter tested applying 50 percent of the checkbook method by applying exactly half of the recommended amount each time irrigation was required.  He used this modified method for two years to see how the crop responded.  

“We obtained favorable yields out of reducing (the water recommendations) by half, but I knew that was way too low and that farmers would not feel comfortable irrigating this little,” he said.

Porter then set his sights on the Food and Agriculture Organization (FAO) to find peanut crop coefficient data. The crop coefficient is a scaling factor that accounts for crop age, growth and development. He combined this data with 15 years of research from UGA College of Agricultural and Environmental Sciences’ Georgia weather stations and calculated a new state crop evapotranspiration average.

Through this formula, Porter produced a new peanut water-use curve that reduces the checkbook method’s water requirement down to 18 inches. Porter and his team believe that peanuts don’t require as much water as was once calculated, possibly due to emerging varieties.

“We feel like the varieties that are being produced today are more efficient,” he said.

Porter stresses that growers who use the checkbook method will still need to monitor rainfall and subtract that amount from the total amount required by the crop for each week. He also cautions farmers that the checkbook method won’t be an exact fit in years that are either wetter or drier than normal, as it will overestimate or underestimate water needs in those years.

For more information on the UGA Extension Peanut Team and its research, visit peanuts.caes.uga.edu.

(Bryce Ethridge is an intern on the UGA Tifton campus.)