As more farmers have moved to multiple inlet rice irrigation or MIRI and furrow-irrigated rice, it might be easy to forget that more than half of the rice acres in a state like Arkansas, for example, are still grown with levee-gate, flood systems.

So how can those growers conserve water in a system that, basically, uses gravity to allow water to flow from the topmost rice paddy through a series of levee gates to lower-level basins before running out the bottom of the field?

Joe Massey, an agronomist with the USDA-ARS Delta Water Management Research Unit, believes the automated early cascade rice irrigation shutoff or AECIS system could use new automation techniques to help growers shut off their irrigation wells before they pump water out the bottom end.

Massey and Clay Smith, a producer from Greene County, Ark., discussed new measures for conserving irrigation water during the 24th annual Arkansas Soil and Water Education Conference, which was held online this year.

“If you look at the way that rice is irrigated, cascade, levee-gate flood still accounts for the majority (54 %) of the rice acres,” Massey noted. “About 32% of our rice acres in Arkansas are using multiple inlet irrigation. Furrow or row rice is really growing, and, as of 2020, it’s about 12%, and alternate wetting and drying flood management or AWD is around 3%.”

Cascade flow

On the Smith Farm, located near Walcott in northeast Ark., about 80% of the rice acres are irrigated using multiple inlet rice irrigation, said Smith. “We have some furrow-irrigated or row rice, also, and we have about 100 acres that’s in cascade flood, There are some fields where MIRI just doesn’t work.”

In a cascade flood system, “you build up this cushion of water that flows down,” said Massey. “We know that farmers try to time stopping the irrigation so that a whole bunch of water doesn’t run off the field.”

Massey believes more automation becoming available will make it much easier to time shutting off the cascade flood before water leaves the bottom of the field.

“In this simple model, we have a 10-paddy, straight levee field,” he noted. “If we were to put a flood-depth sensor in the eighth paddy of that field and use the flood-depth sensor to inform the farmer the eighth paddy was now full that would be the first level automation.

“The farmer can then decide if they want to drive down and turn the well off, or we could have the sensor shut the well off automatically,” he said. “Or the sensor could control a system with auto valves that would rotate the water to some other field. Again, those are the different levels of automation we talked about before.

“But, in this AECIS concept, we would run water into paddy eight until it’s full and shut the irrigation off. The next two paddies would serve as catch basins for the excess irrigation and uncaptured rainfall to irrigate the two bottom paddies, which represent 20% to 25% of the field area. The other concept is we would manage those bottom paddies using alternate wetting and drying agronomics.”

To see the presentation, click on the 2022 Arkansas Soil and Water Conference icon at www.arkswec.com.