If every soybean grower in the delta region of Mississippi could eliminate just one irrigation during the season, it could halt the overdraft of the aquifer that has been occurring in recent years — plus saving money, labor, and time, says Jason Krutz.

And he said at the Mississippi Agricultural Consultants Association at their annual meeting that preliminary research data indicate this could be done prior to soybeans’ R-3 growth stage without adversely affecting yield.

(Editor's note: Dr. Krutz and Dr. Darrin Dodds, assistant Extension professor at Mississippi State University, will present a special Irrigation Technology Seminar at the Mid-South Farm and Gin Show Friday, March 1, at 1:15 p.m. on the mezzanine level of the Cook Convention Center.)

“We’ve run the mathematics on it, and eliminating one irrigation would pretty much take care of the overdraft on the aquifer,” he says.

Aside from the water conservation aspects, says the associate Extension and research professor at the Delta Research and Extension Center, Stoneville, Miss., growers are concerned about increasing regulations on withdrawal of water from the aquifer in the years ahead.

“Right now, there are proposals on various tables suggesting that 10 percent to 20 percent of our existing irrigation wells could have meters put on them, and as early as 2015 that data could be provided to regulatory agencies for monitoring.

“Producers are concerned that there will be restrictions on water use in the future. Consequently, Mississippi State University research and Extension personnel are being proactive in developing systems that can maintain or improve yield and profitability, if permitted values are strictly enforced — 18 inches per year for corn, cotton, and soybeans, and 36 inches per year for rice.”

Krutz, who assumed his position last May, says the Mississippi Soybean Promotion board is funding the research to determine if there is a stage in soybean development when water stress can be tolerated without having an adverse effect on yield.

Studies were done last year, he says, using different irrigation initiation and termination times, “trying to identify periods during the growing season when we could potentially stress the soybean plants without having an adverse impact on yield.”

Several different irrigation scenarios were used for comparison against a standard.

Eliminating two irrigations at the R-3 growth stage resulted in a 10 percent yield loss, Krutz says, and eliminating three irrigations from R-3 to R-5 resulted in an 18 percent to 20 percent yield loss.

“But the data suggest there is a zone where we could potentially stress soybeans — perhaps all the way through R-2 — and not have an adverse yield effect. From R-3 on, however, we saw that if we put stress on the plants we were going to get a serious adverse yield effect.”

Using a scientific irrigation scheduling tool and stressing the plants through R-2, then initiating irrigation at R-3, only four irrigations were applied, but yields were equivalent to the six irrigation standard treatment.

“We’re hoping this year to have studies at 10 to 12 locations to see if these results hold up and if we can reliably eliminate irrigation through R-2 without yield loss,” Krutz says.

With the increasing use of irrigation in the Delta, he says, most growers could benefit from the use of an irrigation scheduling tool.

“I’ve asked a lot of producers, with acreages ranging from 1,000 to 16,000, how many irrigation sets they have during a season, how many fields they irrigate, and how they keep track of those irrigations. Probably 95 percent can’t tell me how many irrigation sets they have.

“In today’s technology-driven agriculture, we’re generating data galore and zapping it everywhere electronically — yet when it comes to tracking irrigation and water use, in many cases we’re still in the Stone Age.”