Furrow irrigated rice is rising in popularity. Furrow irrigation has several benefits, namely saving time and money when compared to a flooded rice field system.
Jarrod Hardke, a Professor and Rice Extension Agronomist for the University of Arkansas System Division of Agriculture Cooperative Extension Service, spoke on management considerations for furrow irrigated rice.
Managing furrow irrigated rice
Over the past few years, the percentage of adoption in the Delta for furrow irrigated rice or row rice has increased.
"In Arkansas, we saw the first big jump of furrow irrigated rice adoption around 2016, and it has been climbing dramatically since then," Hardke said. "Our current estimate was, in 2020, around 14% or about 200,000 acres of furrow irrigated rice was grown in the state of Arkansas. We do expect the number of acres to continue to increase to some degree going into 2021."
Hardke reminded farmers, when thinking about furrow irrigation in rice, to shoot for shallow beds just tall enough to hold water.
"We want to watch out for fields with a bit of a cross or side slope," he said. "Those fields have a harder time keeping the water in the furrow and not jumping beds. If that is happening, you need taller beds, which may not be a fit for row rice."
Their recommendation for bed width is roughly 30 inches on loamy type soil or about 38 inches on clay soil.
"We can certainly go wider than that, but your risk increases to start running into some problems," Hardke said. "The same is going to be true on clay soils if we start getting a lot wider than 38 inches, but the clay is going to be more forgiving than a loamy type soil as far as getting a little too wide. Pipe Planner and Computerized Hole Selection are two tools to help with making furrow irrigation more efficient.
"Also, blocking the bottom of the field to back some water up and contain as much water as the young rice can stand within the field is going to make us a little bit better in our furrow irrigated rice efforts."
Another management tip is to focus on avoiding water stress as rice enters reproductive growth, which is around the green ring to half-inch internode elongation growth stages.
"That's a key period for when we're forming the number of kernels and panicle branches," he said. "Water stress can be one of the factors to hurt formation, but also try to avoid water stress from flowering through grain fill."
In general, drain the fields late.
"Obviously, we're not truly draining most of the field because most of it is furrow irrigated except for maybe the bottom where we're holding water," Hardke said. "However, we want to make one more irrigation after the normal drain timing. Whenever you would think the field would be ready to drain, make one more irrigation because that profile is not saturated the same way it is when we're growing a flooded rice environment. However, if we are backing water up at the bottom of the field, it may be where we can go ahead and turn that water loose at about a normal drain time."
Varieties for furrow irrigation
The researchers at the University of Arkansas System Division of Agriculture did small plot variety trials the past couple of years in furrow irrigated rice systems at the Rice Research and Extension Center at Stuttgart and an on-farm location in Monroe County.
"Focusing on loamy soils, we plant replicated versions of varieties such as Diamond, Jewel, CL153, CLL15, CLL16, etc.," Hardke said. "We plant one at the top of the field right up next to the pipe, and then one at the very bottom of the field."
As the season went on and the rice got bigger, they could hold more water in the field.
"Regardless, whether we're talking about long-grain varieties, medium grains, or even the hybrids, the bottom end of the field, which was holding more water, was doing a lot better than the top of the field," he said. "Anything we're putting right up against the pipe within that first few hundred feet are going to be more difficult to adequately manage, especially the fertilizer component."
As the water moves to the middle and then bottom of the field, the crop's growing conditions typically improve and are better at the bottom where it's more like a flooded rice field.
"Certainly, we want to be very careful with the pureline varieties, so we're not putting them in situations that are too stressful," Hardke said. "Regardless of the variety, the yields typically looked good at the bottom of the fields, but the yields at the top of the fields were lacking somewhat.
"At the top of the field is where we're going to struggle with making sure we get adequate nitrogen and adequate water should you choose to put a variety in a furrow irrigated system, but we can pick out some varieties that did perform a lot better overall."
The hybrids tested did well in a furrow irrigated setting and produced good yields throughout the field. The medium grain varieties looked okay as well. Their recommended varieties are similar to last year's and include XP753, RT 7521 FP, RT 7321 FP, and RT 7301.
"These look to be the safest, more consistent yielders," he said. "However, some other varieties, such as CLL15, CLL16, CLL17, and Jupiter, do maintain some comparative difference in yield with the hybrids."
In field observation, Jupiter, a medium-grain variety, showed a bit more stress in a row rice environment, especially on some steeper fields.
"We generally recommend avoiding Diamond, LaKast, PVL02, and CLM04, for example, in row rice or furrow irrigation," Hardke said. "Varieties like Roy J, CL151, Francis, and Cheniere, we do not recommend for furrow irrigation because of environmental stress factors as well as increased rice blast concerns.
"We lean toward the hybrids first from a recommendation standpoint, but other varieties can and will be players in a furrow irrigated system. Keep in mind, this list is not complete by any means, but these are a few of the varieties we have looked at concerning furrow irrigation."