Hot Time for Irrigation

By Boyd Kidwell
Progressive Farmer Contributing Editor

The Little Red River Irrigation Project has paid a big dividend for farmer Danny Barnett and farm owner Bob White in White County, Ark. Water provided by an on-farm reservoir built with cost-share money from the irrigation project was a lifesaver during last year's drought.

"Rice is our cash crop, and without water, you can't grow rice," says Barnett, who adds the area had a long stretch of dry weather and 28 days with temperatures above 100°F in the summer of 2012.

Fortunately, Barnett built a 27-acre reservoir that averaged 10 feet deep in 2011, the farm's first year of participation in the Little Red River Irrigation Project. Cost-share funds paid 60% of the cost of building the reservoir that stores 270 acre-feet or 88 million gallons of water. White owns the land, and his son-in-law, Barnett, manages the farm that has been in White's family since 1917.

Recycling Runoff

Other practices Barnett put in place under the project include:

-- Constructed a tailwater recovery system. This large ditch captures field runoff water from smaller ditches and stores the water until it can be pumped back into the reservoir for reuse.

-- Cleaned neighboring ditches. With permission from neighbors, Barnett has cleaned their ditches so runoff water from 260 acres on his farm and 100 acres of neighbors' land is collected in the tailwater recovery system. In addition to conserving groundwater, recycling runoff water prevents sediment and crop nutrients from reaching streams and rivers.

-- Installed a power plant. The plant pumps water from the tailwater recovery system into the reservoir and from the reservoir through a pipeline to risers in the field.

-- Laid pipelines. The new lines carry water from the reservoir to field risers.

-- Precision-leveled the land. Precision-leveling makes efficient use of furrow-irrigation water.

Barnett grows his crops in a rotation of two years of soybeans and one year of rice. Soybeans furrow-irrigated on precision-leveled land yielded 44 bushels per acre despite the 2012 drought. Soybeans grown on land that wasn't precision-leveled averaged only 20 bushels per acre.

Noting those results, Barnett plans to have the remainder of his irrigated acres precision-leveled using cost-share money.

Thanks to water from his reservoir and flood irrigation, Barnett had his best rice yield ever in 2012, with an average of 178 bushels per acre (dry weight). However, due to the long string of 100 degree to 115 degree Fahrenheit days, part of his rice crop was of poor quality, and the price he received reflected it.

Rice is a water-demanding crop well-suited to precision-leveled fields. After rice is planted and reaches a height of 7 inches, the fields are flooded with 3 to 4 inches of water, and remain flooded for six to eight weeks. It's work that requires close monitoring. During hot weather, the evaporation rate may average 0.5 inch per day.

In a normal year, a rice crop requires approximately 2 acre-feet (24 inches) of water per acre, and soybeans require 1/2 acre-feet (6 inches). Because of the hot weather and high evaporation rates in 2012, Barnett used all of the water stored in his reservoir and purchased additional water supplied by a neighbor's pipeline. In a normal year, the Arkansas rice grower says the reservoir will provide adequate water to irrigate his crops.

"We've invested some money and a few acres of cropland into the tailwater recovery system and reservoir, but having water for irrigation is worth the investment," Barnett says. Without the new reservoir, Barnett wouldn't have planted the rice.

SAVE THE AQUIFERS

"Water conservation is what it's all about," says row-crop farmer Keith Watkins, of Griffithville, Ark. "Our area has been designated as a critical groundwater-use area. Being more efficient with surface water has cut my use of aquifer water by 50%."

Under the 60% Little Red River cost-share program, Watkins has built water-storage reservoirs of 80 acres and 5 acres to irrigate 950 acres of crops. Watkins and his son Bradley grow rice on flood-irrigated fields. As part of a crop rotation, Watkins grows soybeans on furrow-irrigated land and has recently started growing corn. He serves on the irrigation district board and has worked in support of the Little Red River Irrigation Project since 1980.

Watkins has built a tailwater recovery system, installed 5.5 miles of underground water pipeline and precision-leveled 500 acres. Using recycled and stored water from the tailwater recovery system and the reservoirs has replaced water that had been supplied by seven wells. Water is such a valuable commodity that the Arkansas farmer recharges his reservoirs with water pumped from a nearby creek after heavy rains.

With irrigation and precision-leveling, Watkins' soybeans average 40 to 50 bushels per acre. His rice averages 180 bushels per acre, and corn 170 to 200 bushels per acre. "This project is all about reducing groundwater depletion. We have an abundance of excess surface water in our area. The problem is having water when we need it to irrigate our crops," Watkins says.

FURROW IRRIGATION FINE-TUNED

Folks who haven't farmed in the Mississippi Delta likely aren't familiar with furrow irrigation. This irrigation technique provides good results in areas with adequate water and nearly level crop fields. To begin the process, a water supply needs to be at the high end of a field. Water is applied to the top end of furrows and flows down the furrows under the influence of gravity.

Furrow irrigation has been fine-tuned with the use of polyethylene pipe and precision land forming (leveling) to improve the efficiency of water use by 25%.

As a field application, poly pipe is a flexible, collapsible tube running along the top end of the furrows. Holes are punched in the poly pipe to release water into the furrows. Smaller holes are punched in the poly pipe near the water source where pressure is highest and larger holes are punched for furrows farther from the source.

Matching hole size with pressure allows water to reach the end of all rows at the same time so that when the pump shuts off the rows have received the same amount of water. Arkansas Extension agents use computer software called "Phaucet" to help farmers determine the best pattern of hole sizes. Poly pipe costs $250 per quarter-mile, enough to irrigate a 40-acre field. The poly pipe is rolled and recycled at the end of a growing season, and new poly pipe is installed each year.

Precision-leveling keeps the water flow down the furrows uniform and prevents ponding. In the Little Red River area, land leveling typically costs $1.55 per cubic yard for 450 cubic yards of soil, or $698 per acre. The cubic yards of soil moved and the cost per acre vary widely between fields.

LITTLE RED RIVER: A PRIVATE AND PUBLIC PARTNERSHIP

The Little Red River Irrigation Project is a partnership between USDA Natural Resources Conservation Service (NRCS) and the Little Red River Irrigation District. The project is a voluntary program that provides financial and technical assistance to help farmers address water quantity and quality concerns in the Little Red River Watershed.

By helping farmers capture and reuse water, the project reduces groundwater depletion and conserves the Alluvial and Sparta aquifers of northeast Arkansas. Because of diminishing supplies in the aquifers, this area has been designated a critical groundwater use area by the Arkansas Natural Resources Commission.

The project is a voluntary program through the Agriculture Water Enhancement Program portion of USDA's Environmental Quality Incentives Program. Danny Barnett and Keith Watkins are two of 37 producers with a total of 17,843 acres under contract. The program intends to treat 34,121 acres for a cost-share of $3.15 million.

"The Little Red River Irrigation Project is a perfect example of what locally led initiatives can achieve with a helping hand from federal and state agencies," says retired farmer and landowner Elvis Vaughn, of White County, Ark. "Partnering with NRCS in our water conservation efforts has helped keep several of us in the farming business because we now irrigate more efficiently."

(BS)

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