image: Thomas Marek, Texas AgriLife Research senior research engineer, explains the effort to grow 200-bushel per acre corn on only 12 inches of irrigation. view more
Credit: Texas AgriLife Research photo by Kay Ledbetter
ETTER – Agriculture is a primary user of water in this region, and corn requires the dominant share. Texas AgriLife Research is joining forces with the Texas Corn Producers Board and North Plains Groundwater Conservation District to help producers try to maximize their water and still produce economically adequate yields, said Thomas Marek, AgriLife Research senior research engineer.
The name of the research-based study is the 200-12 Corn Project. It is being carried out at the North Plains Research Field near Etter, said Marek, superintendent of the research field.
"This is a key area for corn production," said David Gibson, Texas Corn Producers Board executive director at the recent North Plains Corn Irrigation Research and Extension Field Day.
"Our growers are learning a lot about what they need to do with their water," Gibson said.
Part of the impetus to evaluate growing 200 bushels per acre of corn on 12 acre inches of irrigation water was new rules imparted by the North Plains Groundwater Conservation District. These rules lowered pumping limits from 2 acre feet per year to 1.5 acre feet per year by 2012, said Dan Krienke, a water district member.
"However, our board thinks it's a good goal for us to see if we can go farther with the water and get out ahead of the current production curve," Krienke said. "This research here will help us see if it is achievable. We are not planning on changing the district's pumping limits any further, but we want to see what is possible."
Marek said the 200-12 project means a 10-inch reduction of irrigation water, on average, for the corn plots at the AgriLife Research field.
A typical corn crop, watered at 100 percent evapotranspiration or ET, as it is known, would now require about 32 inches of total water and would be expected to yield above 250 bushels per acre, Marek said.
That total water requirement has already been lowered through breeding and irrigation management from the 34-36 inches required on older varieties that produced less yield, he said.
The research plots this summer received 12.8 inches of moisture from rainfall, as opposed to the normal 8 to 10 inches received, so only 8 inches of irrigation were applied to bring the total crop water to 21.6 inches, he said. The target level was 22 inches.
The North Plains Research Field plots are 30 feet wide and 300 feet long, considered huge by some standards, and have been replicated four times, Marek said. Three of the most common hybrids were planted to represent what farmers are using in their fields, so results will not just represent experimental-bred seeds.
This study took more than 100 man-hours to plant and 116 gear changes with the equipment, so it is labor intensive to do this type of study, he said. It is also being subjected to "real world" production scenarios of insect and weed pressure.
Many scientists have participated in data collection from insects to crop development throughout the season, Marek said.
The irrigation protocol was to use the 4-foot-soil profile moisture, which was 5.42 inches of available water at planting time. When that decreased to 50 percent, irrigation began at a rate of 1-1.5 inches per application, depending on what rainfall probability was forecast, he said.
"This targeted irrigation protocol and total water level are what distinguishes this research-based study from other demonstrations within the region," Marek said. "Our intent is to target total water with management control; if it rains a lot, we don't irrigate as much and only then up to 12 inches of irrigation. That's the difference with the study here."
He said while they are evaluating water reduction, he believes through the study they also are seeing the crop growing degree days changing because of the stress caused by limited water.
While the ET network estimates corn ET for a fully watered scenario, this study was designed to also evaluate production at a limited water level and requires the use of a "less than full ET multiplier" for actual crop ET, Marek said.
"It would be nice to have the entire limited water production function determined, but these are difficult and costly to get on this scale of demonstration," he said. "That's why we are doing the multi-level, crop ET work on the other NPRF pivot with Dr. Wenwei Xu. The two studies compliment each other in many ways."
Xu, an AgriLife Research corn breeder from Lubbock, said the two Pioneer and one Monsanto hybrids being used in this study are recommended for both grain and forage. They were planted on May 8-10 and their relative maturity is 115 days.
Marek said the first year of data will be gathered at harvest time, but to ensure that a representative and robust set of data is developed, the study will be repeated under the same protocol and with similar varieties.
The study also is to be evaluated to determine the probability of what results occur the majority of the time and not just on an average basis, he said.
The study has been approved for funding for the next two years by the Ogallala Aquifer Program, as announced by Dr. David Brauer with the U.S. Department of Agriculture-Agricultural Research Service at Bushland.
"Much of this type work would not be possible without the funding support and cooperation of our water partners at Bushland," Marek said.