Corn crop irrigation management key to bottom line

Writer: Kay Ledbetter, 806-677-5608, [email protected]
Contact: Dr. Qingwu Xue, 806-354-5803, [email protected]

AMARILLO – Too much water doesn’t help corn producers make more crop; too little water also takes away from yields. Ongoing Texas A&M AgriLife Research studies are determining a formula for finding the right amount for the right results with other best management practices.

Dr. Qingwu Xue, Texas A&M AgriLife Research crop stress physiologist at Amarillo, said most corn in the High Plains has already been planted, but producers can still affect their bottom line with proper management practices.

Xue and his colleagues have been conducting field research in corn management for years, along with other AgriLife Research and Texas A&M AgriLife Extension Service faculty, in the areas of irrigation, hybrid selection, planting dates and seeding rates.

Each of these management practices plays a role in the overall water use and yield determination of the corn crop, but irrigation management remains the most important issue in corn production, he said.

The average seasonal irrigation for corn is about 20 inches, he said. However, irrigation demand can be much higher in a drought year like 2011.

“Based on our multiple-year studies, we found using irrigation to meet only 75-80 percent of evapotranspiration demand can result in the same yield as meeting 100 percent ET demand in years with an average or above average seasonal rainfall,” he said.

Xue said the water-use efficiency is generally maximized at this irrigation level. Cutting back any more, unless there is good seasonal rainfall and excellent soil water storage at planting, will reduce corn yield.

Research has also shown late planting can potentially save some irrigation water while maintaining the high water-use efficiency, he said. So producers who were held off by wet fields into June won’t be hurt.

Corn planting in the Panhandle typically ranges from late April to late May, but in field trials during the 2013, 2014 and 2015 growing seasons, Xue had some hybrids planted in June and early July.

“We evaluated planting date and hybrid interaction for corn yield and water use,” he said. “The planting dates we used were May 15, June 1, June 15 and July 1. The results from this study indicated that high yield can still be achieved with a longer-season hybrid when planted in the middle of May and early June.

“When the planting date was delayed to late June and early July, mid and short-season hybrids showed the yield advantage over the long season one. However, delaying planting to late June or early July generally will reduce yield potential.”

Xue said hybrid selection is another important factor for corn producers. With drought still the No. 1 concern in corn production in the High Plains, the newly developed drought-tolerant corn hybrids provided significant yield benefits, 10-15 percent increase, under lower irrigation levels in the study.

“However, if you have sufficient water to pump, a conventional new hybrid will yield the same as drought-tolerant hybrids. Hybrid selections include different protection traits and maturity groups. Producers may select the specific hybrids based on specific weather and field conditions.”

For example, he said, 2015 at Bushland was an excellent season to evaluate the ear protection traits due to disease damages to corn ears.

“We saw clear differences in ear damage among hybrids. Some hybrids showed excellent ears without any disease damage but some hybrids had moderate to severe damages, which significantly reduced the grain quality.”

            Xue said producers can also alter their seeding rate according to irrigation level. As a general rule, seeding rate increases as irrigation and yield potential increases. However, determining an optimum seeding rate can save on seed cost while maximizing the yield potential.

“We have evaluated interactions of hybrids and seeding rate at multiple irrigation levels,” he said. “The seeding rate ranged from 26,000 to 56,000 seeds per acre in our trials. At full irrigation level in some hybrids, corn yield increased as seeding rate increased initially, but yield did not increase further at seeding rates higher than 38,000 to 44,000 seeds per acre, depending on hybrids.”

Xue said the current seeding rate used in AgriLife Extension’s corn variety trial at Dalhart and Dumas is 32,000 seeds per acre.

He said a 2015 Pioneer survey regarding seeding rate on corn acres in the U.S. and Canada showed 66 percent of corn acreage is now planted at 30,000-36,000 seeds per acre and only 10 percent is planted at more than 36,000 seeds per acre.

“Based on the literature and our trial results, I would say the 40,000 seeds per acre or less would be sufficient for corn in the Texas Panhandle if your yield target is about 250 bushels per acre,” Xue said.