Earl Kline says multiple-inlet rice irrigation brings precision to a crop where watering is usually anything but precise.
“If you’re a rice farmer, you know that when you turn a well on and turn it off you’re guessing that water is going to make it down the hill to where you want it,” said Kline, a rice producer from Benoit in Bolivar County, Miss.
“There is no way you can improve on that other than being there on top of it and making that decision when it gets there and saying ‘this is close enough. I think it’s going to make it,’ and you turn it off.”
When growers use polytubing for multiple inlet rice irrigation or MIRI, they can put the water in the exact spot in the field where they want it, said Kline, a speaker at the first Delta States Irrigation Conference in Miner, Mo., Dec. 17. The conference was a joint effort of the land-grant universities in the five Delta states, Texas and Kansas.
“If you need water at the top, you pump at the top,” he said. “You go down the field and look at each spill or each pad separately. It takes me about 10 minutes to ride down the turn-row on a 40-acre field and turn around and come back. Say I need water in the top four pads; I’m not pumping water all the way to the bottom of the field.
“The best thing to use is a five-eights-inch rope, tie that polytubing off, have enough gates in the top and with a diesel engine you can idle that engine down. An electric engine is a lot more complicated, but it can be done.”
Kline and Joe Massey, agronomist with the Yazoo Mississippi Delta Joint Water Management District at Stoneville, Miss., have been working together for several years to demonstrate the energy and water savings of MIRI systems. Besides using polytubing for precise water application, they also manage flood depths to maximize rainfall capture and reduce over-pumping.
Water conservation has become more important for Mississippi rice farmers because of the decline in the water levels in the alluvial aquifer that underlies the Delta. In 2014, the Mississippi Department of Environmental Quality began a voluntary metering program aimed at helping growers determine how much water they’re pumping for irrigation.
Kline said he became interested in side-inlet irrigation after he picked up a farm that did not have traditional rice-producing soils.
“All of my ground was heavy, buckshot soils,” he said. “Some of you know it’s the kind of ground that if a bird flows to low, he can stick to the ground. It’s that bad. So I went to a silt loam, cotton farm with 85 percent cotton base, and I was a rice farmer and started planting rice on it.
“A friend told me that if I did not run polytubing across that field I would not keep water on it, and he was exactly right. We have what we in the Mississippi Delta call sand blows. This is between the Mississippi River and the Sunflower River, and there are areas there where the water just percolates through the ground and will not stay there.”
Kline said he had a 120-acre field with one well for watering the rice. He set the irrigation system up so that he could run water in four directions through polytubing and to put more gates in one section than in the others. Most weeks, he would turn the pump on the well on Sunday afternoons and let it run until he had the desired amount of water in each pad.
Flooded in 24 hours
“I can actually take a 40-acre field with silt loam soil, and in 24 hours have it flooded back to the capacity I want, and there’s no question about when I turn it off,” he said.
Training employees to allow the water levels to drop in the bays can also be a challenge. “I had been telling my guys for years to keep the water on the rice,” Kline notes. “Now you’re telling them to let that water down. It takes a big learning curve there.”
Massey and Kline said using intermittent flooding or letting the floodwaters in rice naturally subside to where the rice is sitting in saturated mud can save growers a significant amount of diesel fuel or electricity and money.
“We have seen growers use intermittent flooding in as many as eight wetting and drying cycles,” said Massey. “We calculate that for every inch of rainwater that is captured using this system or groundwater that is not pumped, that’s about a gallon of diesel fuel saved per acre.”
More importantly, yields in intermittently flooded fields have been about the same as in conventionally-watered rice, he notes. And milling quality across a number of varieties in their studies has not been affected.”
Kline says one of the best tools a grower can use to improve irrigation efficiency is a flow meter. "The only way you're going to know what you're doing is with a flow meter to see how many gallons you're using. That's the biggest thing I can tell you to take from this.
"Your savings can be extended through intermittent flooding because you're capturing rainfall; you're able to hold it when it comes and you're not pumping to keep the water at a prescribed level," he noted. "I'm not afraid a two-inch rain anymore. In fact, I'm not that concerned about a five-inch rain because I know I can handle it."
For more about the Delta States Irrigation Conference and useful irrigation water management tools, visit: http://extension.missouri.edu/scott/documents/Ag/Meetings/Irrigation-Conf-2014-Agenda.pdf and http://deltafarmpress.com/management/irrigation-water-management-tools-can-help-producers-more-wisely-use-valuable-resource.