Many of the soybean acres in Michigan are planted in 15-inch rows using split-row planters. These planters are significantly more expensive than planters of comparable width set up for 30-inch rows and producers want to know if the extra expense is justified. The purpose of this trial was to evaluate how two common row spacings affected soybean yield and income in 2019 and 2020.
Two row spacings (15 inches and 30 inches) were compared at two locations in 2019 and six sites in 2020. All trials were planted with planters equipped with interplant/splitter units to ensure that row spacing was the only difference between the treatments. We tried to keep planting rates the same (approximately 130,000 seeds per acre) regardless of row spacing. Stand counts were taken to determine if we achieved this goal.
Final stands for the two row spacings were significantly different at four sites and operator and equipment error were responsible at two of these. At the Tuscola County site, the guidance system was off causing some of the 15-inch rows to be planted directly on the previous year’s corn rows. At the Saginaw County site, the planting rate was not adjusted when moving from 15-inch to 30-inch rows. This site provided further evidence that thin soybean stands can produce surprisingly high yields as 57,300 plants per acre produced the same yield as 102,300 plants per acre (66 bushels per acre).
The 15-inch rows produced higher yields than the 30-inch rows at three of the eight sites. When six of the locations were combined (Tuscola and Saginaw were excluded), the 15-inch rows produced 2.5 bushels per acre more than the 30-inch rows.
Roger Betz, Michigan State University Extension farm management educator, generated a partial budget comparing the economics of purchasing a 12/24 row split-row planter versus a 12-row 30-inch planter. This analysis showed that the 15-inch rows increased income by $2,748 per year over the life of the planter. The assumptions used in the analysis are listed below:
- 15% rate of return on investment
- 2.5 bushels per acre yield increase
- Soybean market price of $9.80 per bushel (10-year projection) minus $0.40 transportation and marketing cost or $9.40 net at the farm.
- 500 acres of soybeans per year
- Planter life of 10 years
- $50,000 higher cost for the interplant planter
- $7500 salvage value
The results from these on-farm research trials show that split-row planters are profitable. However, the yield benefit from planting in narrow rows is reduced when planting early and when planting in high-yielding environments. Also, planting in 30-inch rows is recommended in fields having a history of white mold or that are prone to crusting. Another consideration is that a 30-inch planter can also increase planting capacity by 25% as the price of a 16-row, 30-inch row planter is comparable to that of a 12/24 row planter.
Many Michigan soybean producers plant soybeans in 15-inch rows with air seeders or box drills and they want to know how their equipment compares to a 30-inch-row or a split-row planter. We conducted one trial in 2020 comparing a John Deere 1770 30-inch-row planter to a John Deere 1690 15-inch-row air seeder. The planter improved final stands by 2,500 plants per acre but the yield was the same for both pieces of equipment (64 bushels per acre). Additional research comparing different planting equipment is needed in Michigan. A summary of row spacing/planting equipment research conducted in the U.S. is available at: MSU Cropping Systems Agronomy – Soybean.
This article was produced by a partnership between MSU Extension and the Michigan Soybean checkoff.