Use Of Sodium Chlorate As A Harvest Aid
MANOCH KONGCHUM
RAYNE, LOUISIANA
Timely harvest is one of the most critical factors affecting rice grain quality and profitability. In Louisiana, rice producers frequently encounter weather-related challenges during the harvest season, including rainfall, high humidity, and delayed field access, which can slow grain dry-down and increase the risk of lodging and grain quality deterioration.
Harvest aids such as sodium chlorate have become an important management tool in rice production for accelerating crop dry-down and improving harvest efficiency, particularly when adverse weather conditions delay natural field drying. Sodium chlorate acts as a desiccant by rapidly removing moisture from green plant tissue, promoting more uniform crop maturity and allowing earlier harvest operations. Research from Arkansas and other rice-producing regions has shown that sodium chlorate can effectively reduce grain moisture and facilitate timely harvest when applied at appropriate crop maturity stages. However, improper application timing or delayed harvest following application may negatively affect grain quality, especially head rice yield.
Recent studies at the LSU AgCenter H. Rouse Caffey Rice Research Station evaluated the effects of sodium chlorate application rate and harvest timing on milling quality of three rice varieties: PVL03, RT7421FP, and Titan. Results indicated that sodium chlorate application rate had little effect on milling performance. No significant differences were observed between application rates of 3 qt/A and 6 qt/A for either total milled rice or head rice yield (Figure 1). Average head rice values were nearly identical between the two rates across harvest timings, suggesting that increasing the application rate above 3 qt/A provided no measurable milling quality advantage.
In contrast, harvest timing following sodium chlorate application had a substantial effect on milling quality. Harvesting at 3 or 7 days after application maintained the highest head rice yields, averaging approximately 62% across the three varieties. Delaying harvest until 10 days after application reduced head rice by about 4–5 percentage points, with average head rice decreasing from 61–62% to approximately 56%. More severe losses occurred when harvest was delayed to 14 days after application. Head rice declined by approximately 15 percentage points in PVL03 and RT7421FP and by as much as 23 percentage points in Titan. Average head rice across varieties dropped to about 44%, indicating significant deterioration in grain quality (Figure 2).
These findings demonstrate that while sodium chlorate can be an effective harvest aid, harvest timing is considerably more important than application rate for preserving milling quality. To minimize losses in head rice yield, producers should plan to harvest treated fields within 3 to 7 days after application rather than delaying harvest for extended periods. ∆
MANOCH KONGCHUM
LSU AGCENTER
Figure 1. Effect of the rate of sodium chlorate (3 qt/ac and 6 qt/ac)
Figure 2. Effect of harvesting time after application of sodium on head rice percentage (%). H. Rouse Caffey Rice Research chlorate on head rice percentage (%). H. Rouse Caffey Rice Station, 2025. Research Station, 2025.
