- University research has supported early soybean planting however, there are some risks associated with early planting.
- Risk mitigation includes seed product selection, a weed–free field, seed treatments, stand establishment, and other agronomic considerations.
- Consider using seed treated with an insecticide for bean leaf beetle (BLB) protection and with fungicides to protect seedlings from soil-borne pathogens.
Early Soybean Planting
Early planting can help maximize yield potential, despite cold soil temperatures and slow seedling growth. Although the ideal soil temperature for rapid soybean germination and emergence is between 77 and 86 °F, soybean seeds can germinate when the soil temperature is about 50 °F. However, soybean emergence may take as long as two to three weeks under cold soil conditions.
When planting early, it is important to wait until good soil and seedbed conditions exist. Planting when soil is too wet can result in compaction, poor seed placement, and poor stand establishment. Excessive tillage or a heavy rain soon after planting can result in soil crusting, which may lead to a reduced stand. Soybean seed planted into wet soils will likely negate any yield advantage from planting early. Table 1 lists factors associated with early planting that can help maximize yield potential.
University Research Studies
- Data collected from the Michigan Soybean Yield Contest showed that the average planting date for the high-yield producers was May 4th, 13 days earlier than that of the low-yield producers.1 In addition, the high-yield producers averaged 10 more pods per plant than the low-yield groups, due to plants developing more nodes on the main stem.1
- Yield losses of 0.25 bu/acre occurred in poor growing conditions and losses of 0.6 bu/acre occurred under good growing conditions for each day soybean planting was delayed after May 1st in Nebraska.1
- Iowa State University found that most farmers can increase yield by three to four bu/acre by planting early.2
- Minnesota trial results indicated maximum soybean yield was obtained when the planting date was between May 1-15.3
- North Dakota research showed that late plantings resulted in lower soybean yields, seed quality, and seed oil content and shorter plants. In addition, seeds were set lower to the ground in late plantings compared to those planted on the optimum planting date, which was no sooner than five days before the average last killing frost in the spring.4
- Two-year research trial in Indiana found that soybean yields were higher when planting dates were late April or early May, due to more pods per unit area.5
Along with benefits, planting early can also have a negative impact on soybean yield potential. The management practices recommended to help limit some risks associated with early planting are listed in Table 2.
1Staton, M. 2011. Planting soybeans early offers many benefits. Michigan State University Extension. http://msue.anr.msu.edu/news planting_soybeans_early_offers_many_benefits
2Pedersen, P. Soybean planting date. Iowa State University Extension. http://extension.agron.iastate.edu
3Severson, R. 2013. Soybean planting date and delayed planting. University of Minnesota Extension. http://www.extension.umn.edu/agriculture/soybean/planting/soybean-plantingdate-and-delayed-planting/
4Berglund, D.R. and Helms, T.C. 2003. Soybean production. A-250 (Revised). North Dakota State University. https://www.ag.ndsu.edu/
5Roozeboom, K. 2012. Soybean planting dates: Is earlier a good Idea? AG Professional. http://www.agprofessional.com/
6Davis, V.M. and Nafziger, E. 2009. April showers bring May planted soybeans, we hope! The Bulletin No. 6 article 9. http://ipm.illinois.edu/
7Pocock, J. 2010. 7 ways to attain ultra-high soybean yields. Corn and Soybean Digest. http://cornandsoybeandigest.com/soybeans/7-ways-attain-ultra-high-soybean-yields
8Specht, J. 2010. Three reasons why soybean planting date matters. CropWatch. University of Nebraska-Lincoln. http://cropwatch.unl.edu/cropwatch-april-16-2010-three-reasons-whysoybean-planting-date-matters
Web sources verified 04/13/16. 140405061002
Soybean yield potential is often affected by planting date. University research results have shown that early planting can help maximize soybean yield potential. The potential yield benefits can be achieved by managing risks to early planting with improved technologies and tools.