North Dakota State University’s traditional recommendation for an established soybean plant population has been 150,000 plants per acre across all row spacings. From 2008 to 2019, NDSU has been collecting planting rate by row spacing data. The large dataset has allowed NDSU to reevaluate the current soybean planting recommendation.

In the dataset, soybean planting rates ranged from 60,000 to 220,000 pure live seed per acre and row spacings ranged from 7 inches to 30 inches. Test plot data was collected from across the whole state. Below is the summary of the dataset:

  • Across North Dakota plot locations and row spacings, the planting rate of about 170,000 pure live seed per acre optimized soybean seed yield, while optimum yield occurred with 180,000 and about 140,000 pure live seed per acre in eastern and western North Dakota, respectively.

  • In eastern trials, 8% of planted pure live seed per acre did not develop into viable soybean plants. Assuming 8% of pure live seed does not result in established planted across North Dakota, and using 170,000 pure live seed per acre, about 155,000 plants per acre would be expected to maximize yield.

  • Across North Dakota or by regions, narrow rows (less than 15 inches) consistently provided the greatest soybean yield.

  • In eastern North Dakota, the combination of narrow rows (12 to 14 inches) and planting rates of about 170,000 pure live seed per acre provided optimum yield. If planting in wide rows (24 to 30 inches), planting rates to reach the optimum yield were about 190,000 pure live seed per acre.

  • In western North Dakota, the combination of narrow rows (7 to 10 inches) and planting rates of about 150,000 pure live seed per acre provided optimum yield.

A new NDSU Extension publication, “Soybean Response to Planting Rates and Row Spacing in North Dakota (A1961), has just been published that explains the dataset and goes into more detail about the concluded summary. The publication can be found online at: www.ag.ndsu.edu/publications. For more information, contact Alicia at the Extension office at 701-252-9030 or alicia.harstad@ndsu.edu.