Graduate Student Research Highlight: Getting Rice Off To A Strong State – A Look At Starter Nitrogen Trials

JACOB FLUITT

BATON ROUGE, LOUISIANA

In South Louisiana, early-season weather doesn’t always cooperate, and that can slow the growth of seedling rice. Could a small nitrogen boost at or near planting help rice seedlings get ahead? This question has led me to my graduate research project under Dr. Kongchum, where I’m planning to get a better understanding of starter nitrogen applications in rice. 

Nitrogen (N) is the most limiting nutrient for rice and crucial for grain yield. Its management can vary depending on planting and water management practices. For drill-seeded rice with delayed flooding, most nitrogen is applied at the 4–5 leaf stage before permanent flood establishment, followed with the remainder at midseason (green ring). In some cases, one single preflood application is used where 100 percent of N is applied. 

Recommended planting dates in southwest Louisiana are February 25th to March 20th. Rice planted in this time frame provides the potential for the highest yields and grain quality, while also increasing the potential of producing a second (ratoon) crop. However, in South 

Louisiana, weather during these months can fluctuate dramatically, shifting from ideal conditions for rice growth to unfavorable ones. Variability in temperature and soil moisture, which is often paired with herbicide injury, slows early growth, delaying time from emergence to the 4–5 leaf stage (Figure 1). 

In anticipation of these possible unfavorable growing conditions, the idea of applying a small amount of N fertilizer (Starter N) at or near planting could potentially give young rice plants an early boost. The idea is simple: help seedlings grow faster, compete better with weeds, and possibly allow permanent flood earlier, potentially reducing herbicide applications. 

Applying starter N adds additional cost to current recommended rice management practices, raising some important questions. The main question is whether this application will lead to higher yields? To answer this question a preliminary starter N trial was conducted at the Rice Station in 2024 and 2025. Yield results differed for each year. In 2024 we saw moderate yield increases in the range of 6-12% (3 to 7 barrels per acre) in response to starter N applications. Yield increases in 2025 were none too slight with increases of 1-4% (1-3 barrels per acre). In both years trials were planted the second week of march, but early growing conditions in the 2024 season presented several challenges compared to 2025. 

More days of cooler temperatures and multiple 2-plus inch rains delayed permanent flooding until mid-May which was 64 days after planting. The growing conditions for 2025 were much more favorable and a permanent flood was established the second week of April just 37 days after planting. While the variable results may raise questions about whether the additional cost of starter N is justified from a yield standpoint, a noticeable agronomic response to starter N applications was observed, which could offer potential benefits to a rice crop. As you can see in Figure 2, plots that received starter N, specifically ammonium sulfate, showed to be greener in color and have a greater canopy when compared to no starter plots. 

Based on these results and observations, moving forward we plan to take this research further. By collecting and analyzing key plant and soil variables, and conducting this study over multiple years to capture a range of environmental conditions, this research aims to answer some important remaining questions: 

• How efficient are these early N applications, and should they count toward total season N needs? 
• What is best growth stage for starter N applications? 
• Do starter N applications pair better with single preflood applications or a split application? 
• Which source of starter N provides the best results? 
• Does it provide increased canopy cover and earlier flooding, providing weed control advantages? 

By answering these questions, it will allow us to provide information rice producers need to determine whether starter nitrogen applications can offer measurable agronomic benefits that lead to economic returns.   ∆

JACOB FLUITT

LSUAGCENTER