Reducing row spacing is one way to increase yield and profitability.
Marion Calmer of Calmer Cornheads and Calmer Farms Independent Research in Alpha, Illinois, has found, based on a 4-year study (2009 to 2012) the more profitable row spacing was 15-inch compared to 30-inches. Of course, the price of seed has gone up as well from $15 to $20 per acre (before Roundup Ready) to $65 to $70 per acre today and seeds per unit have dropped to a standardized 140,000 per unit seeds instead of a 50 lbs. per unit.
Soybean row spacing practices have changed over the last couple of decades. Drilling was popular before the introduction of Roundup Ready soybeans because growers relied on soybeans competition to keep weeds subdued. Then growers moved to 15-inch split planters to narrow up soybeans for high yield. Then growers moved to 30-inch larger planters, using the same planter for corn and soybeans, and lost out on some of the yield advantage presented by narrow rows. Maybe the slow move to 20-inch and twin row corn will be a benefit soybeans as they will be planted in narrower row spacing.
Calmer has studied soybean row spacing and populations on his farm for many years. For example, he plants soybeans in 25,000 increments from 50,000 to 200,000. His 5-year study from 2010 to 2015, with soybeans value at $12 per bushel, showed that 75,000 was the most profitable planting population, but that 100,000 make the most sense.
He also looked closely at 15-inch and 30-inch row spacing and found a 6 bushel gain in 15- over 30- inch rows and a 4 bushel gain averaged over 4 years.
Calmer concluded that based on $12 beans and a 6 bushel gain, he earned $72 more per acre income. Calmer stated “At my farm with $12/bu soybeans, 15-inch rows were $48 per acre more profitable than 30-inch rows.”
Narrowing up row spacing is not an easy economical decision today because it means adding more row units to a planter. Nevertheless, if you could achieve consistent 4 to 5 bushel gains or $50 to $70 per acre, the switch is probably justified. However the key mystery is achieving that additional 4 to 5 bushels
Growers can drop their seed rates and still maintain yield and save money on seed.
Let us know in the comment section what row spacing you plant at and if narrowing up rows is a future goal.
Agronomist Dr. Daniel Davidson posts blogs on agronomy-related topics. Feel free to contact him at firstname.lastname@example.org.