By Ryan McGeeney
- Rice producers sometimes rely on flushing to preserve stands, especially in early stages of growing season
- Above-ground reservoirs key to saving money, avoiding tapping groundwater aquifers
- Financial assistance available for establishing reservoirs
Even in the best of years, the need for “just enough, not too much” rainfall is a tough tightrope to walk for row crop farmers throughout Arkansas and beyond. But in this year, with profit margins for rice already thin and a large percentage of 2017’s planned rice acreage already planted, garnering adequate rainfall is more critical than usual.
According to an April 24 report from the U.S. Department of Agriculture’s National Agricultural Statistics Service, about 84 percent of all planned rice acreage had been planted as of April 23. At this time last year, about 72 percent of planned rice acreage had been planted; the five-year average for this point in the season is 51 percent. Planting progress in rice for 2017 is the second fastest ever, falling just short of 2012’s record (85 percent of that year’s planned rice was already in the ground by this point).
While last week provided solid rains for the northwest and north central portions of the state, rainfall for the eastern half of the state hit average or slightly below average amounts. Jarrod Hardke, extension rice agronomist for the University of Arkansas System Division of Agriculture, warned that while emergence has been “a little sporadic but mostly uniform” in his weekly Arkansas Rice Update newsletter, some areas have missed needed rainfall and were “forced to flush to get emergence.”
“When soil dries out too much after planting, it forms a crust, which can prevent the crop from emerging,” Hardke said. “Depending on the soil type, it can actually dry out all the way down to the seed, and risk killing the plant.”
Hardke said that in such situations, growers will often choose to “flush” their rice fields, piping in water in lieu of rainfall in order to force a shallow flood quickly across a field, loosening the soil enough for the plants to emerge.
“It can be a pretty significant investment if you have to flush — $10 or more an acre,” Hardke said. “But in a year when profit margins are already razor-thin, and your input costs are already sunk into the field, that’s a better option than just losing your stand entirely.”
Flushing from ground water, said Hardke, isn’t favored from either an economic or a water conservation standpoint. The slow depletion of the major aquifers running beneath the land have become an increasing concern for everyone from farmers and agronomists to conservationists and environmentalists.
Many growers choose to use surface water whenever possible to flush or otherwise irrigate their fields. While streams, ditches or lakes can sometimes provide accessible water, building reservoirs and tail-water recovery systems to hold massive amounts of rainfall and runoff is a more reliable solution.
Kevin Cochran, a District Conservationist with the Natural Resources Conservation Service in Lonoke, said the most common options are use of a tail-water recovery systems, which include tail-water ditches, with an irrigation regulating reservoir, or, in the best case scenarios, an irrigation storage reservoir to capture water runoff.
“That reservoir will be anywhere from 8-10 feet deep, and hold ample water to apply onto the cropland fields during the season,” Cochran said. “That water will be captured and held during the winter, when we’re getting additional rainfall, and it will be stored for the beginning of irrigation season, as well as once it is applied runoff can be recirculated throughout the growing season.”
Cochran said it takes about two acre-feet of water to adequately saturate one acre of rice (one acre-foot is equivalent to about 325,851 gallons). The above-ground reservoirs are constructed of earthen levees; Cochran said he had helped plan and design reservoirs ranging from 20-300 acres.
The cost of constructing such reservoirs can be significant. Cochran said that to construct a 40-acre reservoir, for example, would require about 100,000 cubic yards of dirt in order to construct a levee that meets NRCS standards.
“It depends on the cost of fuel, really,” he said. “Right now, contractors are charging about $1.50 a cubic yard, to move it and shape it, using tractors and dirt pans. So we’re easily looking at a $150,000 project. And that’s just the dirt to construct the impoundment. Then we have to include the reliefs and power units just to get water into the reservoir; then we need pumps and pipelines to get water from the reservoir and out on the fields.”