Farmers along the Red River in northwestern Louisiana are looking at the river in a new way — as a source of water to irrigate their crops.
The LSU AgCenter is working with the Caddo Soil and Water Conservation District, the U.S. Department of Agriculture's Natural Resources Conservation Service, the U.S. Army Corps of Engineers and area agricultural producers to create a plan to lift water 40 to 50 feet from the Red River in northern Caddo Parish over the levee and into Red Bayou. Farmers will then use water from Red Bayou to irrigate 10,000 to 14,000 acres of cropland.
A proposal seeking $2 million for this demonstration irrigation project has been presented to the U.S. Department of Agriculture to cover studies, installation and construction. Eddie Millhollon of the LSU AgCenter said the project could be operational by 2005 and stands to have a major impact on how crops are grown in the region.
However, Millhollon said, there is one concern with using the river as a source of irrigation.
“Historically, the river is known to have had high levels of salt,” Millhollon said. “The salt that is contaminating water in the Red River basin today was laid down in the Permian geologic age — 220 million to 270 million years ago.”
The researcher explains that an inland sea became isolated and evaporated, leaving the salt behind. Over time the salt was covered with rock and silt. But even today some of the salt deposits are only 50 feet deep.
“There are several streams that flow over these deposits, pick up large quantities of salts and then carry them to the Red River,” Millhollon said.
While some crops can't use water with too much salt, cotton is relatively salt-tolerant.
Dan Logan, a Gilliam, La., cotton producer, has been farming on Red River land since 1959. Today, he and his son Stephen grow 2,500 acres of cotton on their property. Half of the crop is irrigated; half isn't. And three years ago, they began to use the Red River as a source of irrigation water.
“We can definitely see a difference in irrigated and non-irrigated fields,” Dan Logan said. “We're getting better cotton and higher yields in the irrigated fields as opposed to the non-irrigated fields.”
Salt levels have not been excessive, “clearly fine for cotton,” Logan said.
Cotton has a salt threshold level of about 5,000 parts per million (ppm), Millhollon said. Monitoring of salinity for the Red River from 1974 to 2001 shows that although salts did reach levels as high as 1,000 ppm, they averaged about 450 ppm over the period — levels that should not be problematic for cotton.
Stephen Logan said irrigating from the river would be better for the environment.
“If we use surface water to irrigate with, we won't be depleting the aquifers,” he said. “Right now, we have to pump water out of wells to irrigate our crops. With this project, we will be taking water from the Red River and running it into Red Bayou for distribution.”
According to the “Red Bayou Irrigation Demonstration Project Resource Plan” provided by the NRCS, two aquifers serve as a source of groundwater for the Red Bayou Watershed.
The Carrizo-Wilcox, the deeper of the two aquifers, occurs at depths from 100 to 650 feet. This aquifer is low yielding, with 30 to 150 gallons of water per minute. It is generally unsuitable for irrigation because of the high sodium concentrations.
The Red River alluvial aquifer is the largest source of fresh water in the Red River Valley. It occurs at depths of 100 to 250 feet and is capable of yielding 500 to 2,800 gallons of water per minute. But this aquifer is not fully used because of its high iron, calcium and magnesium content.
Research by Millhollon and other LSU AgCenter researchers shows that the quality of water from the Red River is suitable for irrigation provided certain precautions are taken.
A. Denise Coolman writes for the LSU AgCenter.