What’s more, once his family witnessed the ease with which he set up and operated the new irrigation system, they immediately switched to side-inlet irrigation on all of their rice acres.
That was last year, and Dulaney Farms of Clarksdale, Miss., is apparently sold on side-inlet irrigation with plans to use the system on all of their acres again in 2003.
In a side-inlet irrigation system, flexible plastic pipe is run down the side of the field, watering the field from side to side instead of from end to end. The system provides water to each cut in the field at the same time through holes in the plastic pipe. Proponents of the system say it waters a field more quickly, saves water and labor, reduces energy costs and improves weed control.
“We estimate that we used 25 percent less diesel fuel with this system, and we had our highest rice yields ever in 2002,” says Dulaney.
“It was amazing. We could go four to five days on a 100 acre field without turning on a well because it held the water so well, and we didn’t have water running down the field and spilling out of our gates. It worked so much more efficiently than a conventional rice irrigation system.”
Decreased watering time was one of the first benefits the Dulaneys noticed.
“We weren’t trying to pump the water into the top paddy, and then push it across the field,” says Wayne. “It takes a good week to get the water regulated that way. With side-inlet irrigation, the water is regulated the moment you turn on the pump.”
With promises of cost-savings and ease of use, why aren’t more Delta rice farmers using side-inlet irrigation?
Dulaney believes it’s difficult to sell the idea of trying something new when most growers have gotten along just fine with the irrigation system they’ve been using. However, if these same growers tried side-inlet irrigation they’d realize just how easy the system is to operate, he says. “After you get it set up the first time, you see how easy it really is, both to set up and to operate.”
There are many other advantages to the system, including improved weed control, better activation of fertilizer, and a possible yield advantage, according to Dulaney. “
“Watering from the side seems to reduce the effects of cold water on yield. Our yield maps showed more consistent yields with less variation across the field, and what appears to be less stress on the rice in the top paddy,” he says. “This system also allowed us to activate our fertilizer and herbicide treatments more quickly.”
Dulaney does admit he will make one change to his system this year. “In 2002, we ran the 15-10 mil plastic pipe down the side of our turn rows. This year, we’re going to put the pipe about 10 feet from the pad, and let it cross the levees. We believe that will better enable the water to stair-step down the field.”
He says he will also raise his levee gates 1.5 inches higher to act as emergency spillways in case of a big rain.
To determine how many levee gates you need for your field, Dulaney suggests using a grower-devised formula. “The blue three-inch gates have a flow rate of about 70 gallons per minute, and the average rice well has a pumping capacity of about 2,000 gallons per minute. So most rice growers can divide 70 into 2,000 to get the number of gates needed per well. Then you can divide that number by the number of paddies you are actually going to put water into, to get the desired number of gates per field,” he says.
Dulaney also suggests putting the gates toward the top side of the rice paddy to improve water flow.
Extension rice specialist Joe Street at the Delta Research and Extension Center in Stoneville, Miss., suggests growers who haven’t yet tried the system, try out side-inlet irrigation on a few acres in 2003. “Try a little and see if you like it. If you don’t like it you can always go back to your conventional irrigation system,” he says.
Preliminary research data from Delta Research and Extension Center in Stoneville, Miss., suggests that growers lose yield for every day their post-fertilizer flood application is delayed after a fertilizer application.
“If you don’t get the fertilizer water-activated within five days of application, you could be losing 80 to 100 pounds of rice per acre per day, after those first five days,” Street says. “It’s a good rule of thumb to stay within that five-day window.”
Side-inlet irrigation also enables rice growers to get water across the field faster than conventional irrigation systems, further reducing water use. “We figure you use one-third less water with side-inlet irrigation, and at a cost of roughly $1.50 per acre inch of water, you’re looking at a potential savings of $15 per acre,” Street says.
The only downside to the system, according to those who have tried it, is the minimal added cost of the flexible plastic pipe, and the time and labor required to lay the pipe out across a field.
In comparison, conventional irrigation requires you to closely monitor how much water is going over the rice gates, and how the water is moving from paddy to paddy without the water either drying out or running out the end of the field.