Soybean Growers May Benefit from Late-Season Nitrogen Applications
A new study from Kentucky State University has found that applying nitrogen later in the soybean growing season can increase seed protein levels while maintaining both nutritional value and oil quality. The findings offer growers a promising management strategy to improve crop value without compromising seed performance.
The research, published in Frontiers in Plant Science, was led by former Research Associate Deepak Khatri. Dr. Anuj Chiluwal, assistant professor of agronomy and principal investigator of the Agronomy Lab, served as the corresponding author. Additional contributors included Sudip Poudel, Manish Pandit, and former lab member Lalit Pun Magar.
The project expanded on previous research that demonstrated late-season nitrogen applications could raise soybean protein concentration. This follow-up study focused on determining whether the increase in protein affected amino acid composition or the quality of soybean oil.
“We already knew from our earlier study that late-season nitrogen can boost protein concentration,” Khatri said.
“The next question was whether this increase comes with any trade-offs in protein or oil quality. That is exactly what we set out to investigate.”
Researchers conducted field trials over two growing seasons at Kentucky State University’s Harold R. Benson Research and Demonstration Farm. The study evaluated 10 essential amino acids and five key fatty acids in harvested soybean seeds.
Results showed that applying nitrogen at a rate of 80 kilograms per hectare increased the levels of seven essential amino acids and improved oleic acid content by approximately 5%, which is associated with better oil stability. However, sulfur-containing amino acids such as methionine and cysteine did not respond to the treatment.
“The key takeaway is that late-season nitrogen fertilization can improve protein concentration without negatively impacting protein or oil quality,” Dr. Chiluwal said.
“This gives producers confidence that adopting this practice will not compromise the nutritional or industrial value of their soybean crop.”
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