While rice yields have continued to increase over the past few decades, still much work is being done to continue those increases.
LSU AgCenter researcher Manoch Kongchum is the principal investigator of a study on input efficiency, along with AgCenter economist Kurt Guidry, as the co-principal investigator. The goal of his research is to help producers increase their yields, which in turn, means an increase in profits.
“The main objectives include rice variety evaluations, optimum seeding rates, management system evaluation and effects of main and ratoon crop inputs,” Kongchum said.
The project aims to enhance rice production in Louisiana by evaluating and improving nutrient and cultural management practices.
In 2023, four research locations were used to conduct replicated small-plot field trials with approximately 3,800 individual plots. These plots were in Richland, Tensas, St. Landry and Acadia parishes, which provided for a variety of soil type, as well as weather conditions.
“This year we are evaluating 12 recently released varieties, eight experimental lines, two hybrids and one experimental line from RiceTec, and one experimental hybrid from Nutrien,” he said.
These varieties were evaluated for their response to nitrogen application rates and the time of application at the H. Rouse Caffey Rice Research Station in Crowley and cooperator locations in St. Landry, Tensas and Richland parishes.
Preliminary results indicated that the optimum grain yields at the Crowley location required nitrogen ranging from 90 to 150 pounds per acre, with no lodging observed, he said.
Optimum grain yields at the St. Landry location were obtained after applying 120 to 150 pounds of nitrogen per acre. Lodging was observed in these fields when 180 to 210 pounds of nitrogen per acre was applied and some of it can be blamed on hogs, he said.
“Rice variety by nitrogen trials at the Tensas and Richland parish locations will be harvested in a week,” he said in September.
For the second objective, Kongchum and his team conducted trials to evaluate optimum seeding rates for drill-seeded, delayed flood systems at Crowley and Tensas Parish.
Three seeding rates of 15, 25 and 35 seeds per square foot, or 35, 58 and 82 pounds per acre, were established to compare yield performance.
“This year, nine released varieties and four experimental lines were included in the study,” he said.
Preliminary results from Crowley indicated that higher seeding rates were correlated to higher yields even though there were no statistical differences in many varieties.
The optimum seeding rate for DGL2065 and DGM004 was 35 seeds per square foot or 82 pounds per acre, and it was 25 seeds per square foot or 58 pounds per acre for CLL16, CLL18 and the experimental line RU2102150.
For objective three of the study, Kongchum conducted a field trial to quantify border effects on grain yield at the H. Rouse Caffey Rice Research Station.
Preliminary data from this study indicates that small plot trials with plots that are seven rows wide and 16 foot long could result in significantly higher yields than those obtained on a field scale. The conversion factor for actual yield could be approximately 15% to 18% lower than the yield from small plot trials. However, the final adjustment factor will be investigated over multiple season trials to reduce the variation of environmental factors, he said.
The demand for aromatic rice by the U.S. consumers has significantly increased in recent years. The aroma quality is related to several factors.
“Sulfur has been reported as a high correlation with the aroma quality in rice grains,” he said.
A trial was conducted at Crowley to evaluate the effect of sulfur fertilizer, from ammonium sulfate, on yield and aroma quality. Preliminary results show that the yield of aromatic rice variety CLJ01 was not altered by the sulfur rate.
Kongchum said he has multiple ratoon studies that are ongoing.
“These studies are focused on the variety/hybrid response to nitrogen, plant population, nitrogen sources, ratoon growth after first crop desiccation and ratoon stubble manipulation,” he said.
Ratoon trials will be ready to be harvested by the first week of November.
Kongchum said his research plan for 2024 will include variety by nitrogen rate and application timing and seeding rate trials. These two major trials will be focused on the new varieties and hybrids including experimental lines.
The research on border row effects and aromatic rice quality is to be determined. Ratoon and main crop responses to different nutrients, application rates and timings, and stubble management will be continued in 2024.