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Research Highlights
Managing Early Maturing Soybeans in North Carolina

By Barb Baylor Anderson

North Carolina soybean farmers are interested in producing earlier-maturing soybean varieties to capture higher yield potential at earlier harvest dates. Group III and IV soybeans typically have an indeterminate growth habit, which means these varieties allow simultaneous vegetative and reproductive growth in the crop over several weeks.

“Recent analyses conducted on yield contest entries from the past 18 years indicate that the use of an earlier-maturing variety was a strong predictor of high yields,” says Rachel Vann, North Carolina State University Extension soybean specialist, and principal investigator for the research project funded by the North Carolina Soybean Producers Association (NCSPA). “Other advantages of earlier-maturing varieties include premiums for early delivery and the possibility of harvesting before late September/early October hurricanes.”

Vann notes limited research has been conducted on best management practices for early varieties in North Carolina. In collaboration with county Extension agents, Vann established trials in 2018 and 2019 to evaluate row spacing, seeding rate and fertility for both Group III and Group IV varieties. Below are some of the key findings that farmers can consider including in their management plans:

  • Row spacing. Narrow rows (15 or 18 inches) out-yielded wide rows (30 or 36 inches) by about seven bushels per acre and yield advantage was more pronounced in higher-yielding environments.
  • Seeding rates. Earlier maturity groups may benefit from slightly higher populations than what is recommended with later maturity groups in the state. Seeding rates from 60,000 to 160,000 seeds per acre were evaluated, and researchers found yield declined at seeding rates below 120,000 where yield stabilized.
  • Fertility. Soybean nutrient uptake dramatically increases for several nutrients at R1 (beginning flowering). However, this research found that soil-applied applications at R1 had no impact on soybean yield, indicating fertility was not limiting yield or nutrient release was not synchronized with crop uptake.
  • Timely harvest. Earlier-maturing soybeans must be harvested in a timely fashion to protect seed quality. These varieties come into physiological maturity when it is hot, humid and wet, which can intensify issues such as phomopsis and purple seed stain.

Vann currently is looking at optimizing soybean maturity groups and seeding rates across planting dates. Researchers planted Maturity Group II-VII varieties from mid-March to late July in 2020 to learn when early-maturing varieties out-yield traditionally produced maturity groups. 

“If a grower wants to integrate an early-maturing variety into their rotation, they will need to commit to more intensive than normal management and timely harvest to be successful,” says Vann. “It is important to keep in mind other events happening on the farm at the time early-maturing soybeans would need to be harvested before deciding to try these varieties.”

Photos provided by United Soybean Board

This project was funded by the soybean checkoff. To find research related to this research highlight or to see other checkoff research projects, please visit the National Soybean Checkoff Research Database.