Choose the Best Soybean Row Spacing for Yield

By Blake Jackson

Over the past decade, many farmers in southeastern Pennsylvania have shifted from traditional 30-inch soybean row spacing to narrower configurations such as 15 inches or less. However, 30-inch spacing remains common in other parts of the state.

According to research by Daniela Carrijo, assistant professor, and Levi Showalter, research technologist at Penn State Extension, narrower rows can offer several agronomic advantages, though they are not ideal for every operation.

Narrower rows allow soybean plants to distribute more evenly across a field, improving light interception early in the growing season before the canopy closes.

This leads to faster early growth, improved weed suppression, and more efficient use of water and nutrients. A uniform canopy also helps reduce soil erosion and shades out competing weeds sooner.

Studies across the Midwest and Mid-Atlantic regions show that 15-inch row spacing often produces higher yields than 30-inch rows, with gains averaging around 7% in many cases.

However, results are less consistent when comparing ultra-narrow rows, such as 7.5 inches, due to differences in planting equipment and seed placement accuracy.

Narrow rows are particularly beneficial in late planting situations, double-cropping systems, or fields with high weed pressure. They are also advantageous in lower-yield environments where early growth is limited.

On the other hand, narrow spacing may not perform well in drought-prone fields, as plants can use available moisture too quickly early in the season, leaving less water during critical reproductive stages.

Equipment and management also play a key role. Transitioning to narrower rows may require new planting equipment and could increase wheel track damage. Additionally, faster canopy development may raise the risk of diseases like white mold in certain conditions.

Ultimately, selecting the right row spacing depends on field conditions, management goals, and economic considerations.

FAQs:

• What is the most common soybean row spacing?

30-inch rows are still widely used in many regions.

• Do narrow rows always increase yield?

No, benefits depend on conditions like planting time and weed pressure.

• Are narrow rows better for weed control?

Yes, faster canopy closure helps suppress weeds.

• Can narrow rows increase disease risk?

Yes, they may raise the risk of diseases like white mold.

• Are narrow rows suitable for organic farming?

Not always, as they limit mechanical weed control options.

Photo Credit: istock-oticki