Understanding Row Rice Potential, Challenges Is Key to Successful Management

Row rice has had a recent resurgence in the Southern U.S. rice as farmers seek alternative production approaches to improve production and profitability. Many who have studied row rice have documented that there is a large probability that yields will be less in row rice compared to traditionally flooded rice. Reported yield losses have been as high as 20 bushels per acre (900 pounds per acre) on the whole field and as much as 40 (1,800 pounds per acre) bushels per acre from the bottom end of the field compared to the top end of the field. However, the majority of farmers I've spoken with who favor row rice is that they don't see the drastic yield losses and other benefits of row rice outweigh the yield loss they experience.

Converting from flood-irrigated rice to furrow-irrigated rice (row rice) has pros and cons. I'll briefly remind you of the benefits of flood-irrigated rice.

Nutrient Efficiency: The drill-seeded, delayed-flood rice culture has been proven to give farmers the opportunity to reach more than 70 percent nitrogen uptake efficiency. That nearly doubles other high N-using crops like corn and wheat. Furthermore, phosphorus becomes more available in the soil once a flood is established. Phosphorus is critical for rice to make reproductive tillers and reach its optimum yield potential.

Pest Management: For years, flooded soil was the weed control of choice, largely because there weren't many effective herbicides in rice. Flood depth has been shown to be a management tool for blast-susceptible varieties to protect yield potential from significant losses from rotten neck blast. Though the uncontrolled rice water weevil thrives in flooded soil conditions, other pests like chinch bugs and the cattail billbug are issues only when fields are dry.

Row Rice Benefits
The benefits of row rice can be summed up largely in that it may be easier to manage, especially on fields that have greater slope where a larger portion of the field is occupied by levees. First of all, seedling rice when managed under flood irrigation management can suffer from drought stress or too much moisture. Farmers are more hesitant to flush, and residual herbicide activation suffers during periods where no precipitation is received. When the field is in row rice, it is easier for the farmer to make the decision to flush because the labor and setup time are much less cumbersome in row rice compared to flushing in a flood-irrigated management practice. How many times do farmers flush a field that is already pretty drought-stressed only to receive a “chunk-floating” type rain almost immediately after flushing?

Although nitrogen use efficiency is lower, there are some advantages to the row rice production system. Reduced land preparation following soybeans seems to be at the top of the list. Another benefit is managing water on and off the field. By not having a flooded situation, it can be easier to flush a field to activate herbicides and dry it up in a timely manner to apply preflood herbicides by ground application. Producers have also noted that drying the field for harvest has been a benefit.

There appears to be a consensus that hybrids are the only option for furrow-irrigated rice. There are multiple Clearfield® varieties, however, that have been planted in row rice systems with very good results. Horizon Ag varieties CL111, CL153 and CL172 all have multiple blast-resistant genes, including pitA, that give it very good field resistance to most prevalent races of blast fungi. Furthermore, depending on the row configuration and the soil conditions at planting, increasing the seeding rate on Clearfield varieties is much more cost-effective than competitive hybrids.

Finally, in fields where slope is 0.2 percent or less and the tail ditch is closed, the majority of the field (as much as 2/3 of the field) will hold water like a normal conventional flood and/or behave more like an alternate wetting and drying managed field, which has proven to yield equal to or greater than conventional flooded irrigation. On fields where the slope is greater than 0.2 percent, it would not be wise to stop up the bottom tail ditch, especially early in the season, because rice can be stretched due to deep water and cause problems, including excessive yield loss.

The Clearfield herbicide system is an excellent weed control choice in row rice. The residual actives in Newpath®, Clearpath®, and Beyond® herbicides are outstanding tools that are worth including in row rice production systems. Because fields do not have levees, ground rig applications can be made for both herbicides and fertilizer. With these residual herbicides and the ability to flush the field in a timely manner, one would expect excellent weed control.

Many of the questions about managing row rice deal with rates and timing of N fertilizer. Based on recent row rice roundtable meetings hosted by the University of Arkansas, the verdict is still out on a one-size-fits-all fertilizer rate and application timing recommendation. In general, I think we should apply what we know about N uptake dynamics. We know from years of study that the greatest demand for N is from tillering to the beginning of internode elongation. Hence, whether we flood-irrigate or furrow-irrigate, it is important that the bulk of our fertilizer N be applied during that window. The bulk of row rice currently being produced is being managed with three or four application timings. Where three applications are used, typically 50 percent of the N is applied at 5-leaf, and the remaining 50 percent is applied in subsequent applications 7 to 10 days apart. Where four applications are being made, typically equal applications of 100 pounds of urea per acre are being applied at weekly intervals beginning around 5-leaf rice.

As far as N management, the optimum system for N management is the flooded system. My rule of thumb for any field size management is to manage for the majority. Yield losses have been proven to be greatest in the top of the field. I highly recommend fertilizing the field in a manner that will give you the most return on yield. Again, since the majority of the field on fields with less than 0.2 percent slope will be most closely related to a conventional flooded field, I'd manage the majority of the field with normal N rates and application timings. I'd either manage the top side with a spoon-feeding method or understand that yields aren't going to be as high, regardless, so it would be best to just treat the whole field for the majority as that is where most of the yield will come from anyway.

The team at Horizon Ag looks forward to supporting you in 2019, regardless of whether you use traditional flood-irrigated rice or convert to row rice. We're happy to answer any questions regarding best management for high-performing Clearfield varieties and stand ready to work with you to maximize your profit potential in both production systems.

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Photo Row Rice side view