Water shooting out the side of a section of flexible irrigation tubing or Polypipe has become a common sight in the Delta region. But if that water is simply racing across the soil surface toward the tail ditch on the other end of the field the results may be disappointing for the person doing the watering.
Irrigation specialists are trying several strategies to help growers make better use of that resource. One of the newest tools being tested in the Delta states is injecting polyacrylamide or PAM into furrow or sprinkler irrigation systems.
“Research at USDA, the University of California at Davis and some of the other universities in the West have demonstrated that with the use of polyacrylamide you can water less and get the same end results,” says Michael Kenty, product specialist with Helena Chemical Co. Kenty spoke at a field day conducted by A&J Planting Co., SNF Holding Co., and Helena near Tunica, Miss.
“One of the things that is lacking from the data that we’re trying to do is demonstrate with our customers in the Delta states and with Mississippi State University with Dr. Jason Krutz is if we add to what we do water will our yields go up, will the uniformity of the crop improve, will we reduce the sediment in the water like the flocculation test demonstrated.”
Kenty said Helena now has 20 grower trials from Louisiana to the Missouri Bootheel in which PAM is being injected into irrigation water to determine the impact on water infiltration, nutrient runoff and yields.
“The second way the polymer works once it gets into the soil is it will help percolate water more uniformly through the profile, getting a uniform watering and not creating hot spots in the field that can’t be watered well,” said Kenty.
“When you have uniform watering, you have uniform crop growth and uniform yield. Actually, we expect to see increased yield based on some of the work done by USDA and the western universities.”
At A&J Planting Co., the trial was set up so that water without Helena’s Retention polyacrylamide produce flowed out one set of flexible irrigation tubing and with Retention flowed through a second set of polypipe.
“It’s kind of muddy and has that kind of malty looking stuff,” said Kenty, referring to the non-treated irrigation water. “When it runs all the way to the end of the field it will still be full of sediment which is typical of the silt loam soil we have in a large number of our production acres.”
After the initial irrigation, a silt loam soil will typically seal over and the next watering will be less efficient because the water tends to run quickly across the sealed soil rather than infiltrating it, Kenty notes. “When you treat with Retention, you’re getting infiltration of the polymer which will allow for better penetration the next application and better water-use efficiency.”
The application of a polyacrylamide or PAM has been approved by the USDA’s Natural Resources Conservation Service as a best management practice. Listed as BMP Code $450, NRCS has approved a payment rate for the liquid polymer of $22 per gallon under the Environmental Quality Incentives Program. The payment schedule for the solid polymer has not been released.
For more information about polyacrylamide, visit http://bit.ly/polyacrylamide