Can We Save Money On Soybean Seed?
With the cost of Roundup Ready soybean seed increasing, the cost of seed will be a significant input for soybean farmers. While the trend appears to be for increase seeding rates for corn, what about soybeans? In previous articles in 2006 and 2007, I reported local observations on area farms in southeast Nebraska and on-farm research in Nebraska have indicated lower soybean populations may be comparable in yield to higher plant populations that have been used for several years.
Soybean plant population studies conducted in southeast Nebraska indicated lower seeding rates had minimal effect on soybean yields in 2005. At the Darin Keller Farm in Saline County near Wilber, soybeans planted at a population of 100,000 plants per acre (plts/ac) yielded 48.2 bushels per acre (bu/ac) compared to 50.4 bu/ac for a planted population of 175,000. A population study conducted by Mark Caspers showed little difference in soybean yields for a wide range of plant populations. He planted soybeans in 15” rows. Several harvest plant populations of 90 – 100 thousand plts/ac yielded 63 bu/ac; while a harvest plant population of 162,000 yielded 62 bu/ac. In 2005 we had some cold and damp weather and hard driving rains after the soybeans were planted. This reduced the stands significantly from the planted populations (seed drop). Of all the difference populations that Mark planted, the harvest population averaged from 20,000 – 30,000 plts/ac less than the planted population. While this difference may be higher that normal in 2005, the lower plant populations still yielded comparably. In 2006 Mark repeated this experiment in a different field. In 2006 soybean plant harvest populations ranged from 80,000 to 160,000 plts/ac. Yields were consistently about 50 bu/ac for all populations between. In south central Nebraska the Quad County Research Group conducted on-farm trials under irrigation and dryland in 2006 and 2007. In 2006, yields ranged from 65.9 bu/ac for a 90,000 planted population compared to 68.6 bu/ac for the 180,000 planted population in a Fillmore County irrigated study. At most trials the 150,000 planted population yielded the best of any of the populations. In 2007, the Quad County Research Group conducted 7 trails in 5 counties (Fillmore, Seward, Hamilton Clay and York), with planting rates of 90,000, 120,000, 150,000 and 180, 000 seeds per acre. In 5 irrigated fields, yields ranged from 59.4 bu/acre at a seeding rate of 90,000 seeds per acre to 60.2 bu/acre at a seeding rate of 180,000 seeds per acre. In 2007 there were no significant differences in soybean yields in plots planted at 90,000, 120,000, 150,000 and 180,000 seeds per acre. Reducing seeding rates by 40,000 seeds per acre could result in an average savings of $9.00/ac for soybean seed. In 2007 in the Nemaha County area, some farmers cut their seeding rates down to 150,000 seeds/ac and as low as 139,000 seeds/ac with no impact on soybean yields.
The bottom line is, there is potential for substantial savings in seed costs if you currently are planting soybeans at a population over 150,000 plants per acre. The University of Nebraska has recommended soybean seeding rates at 150,000 viable seeds per acre. This is based on several experiments over the years. While the current on-farm research has only been conducted for a couple of years, results were generally consistent from site to site and from year to year and indicated lower planting rates are possible with no impact on soybeans yields. The April 4th issue of “Crop Watch” has an article on soybean seeding rates with results of this on-farm research reported. If you have questions about this issue or are interested in conducting a trial on your farm, contact me at (402) 274-4755.
