Soybean variety selection is one of the more important decisions a grower makes every year. It is crucial for high grain yield and quality, and is the foundation of an effective management plan. Although weather conditions cannot be predicted for the growing season, selecting the right variety can help minimize weather-related risks.
Characteristics to consider
There are many soybean varieties available, which makes selection a challenge. Compared with the options 10 years ago, there are now high yielding varieties with better pathogen and insect resistance, varieties with improved specialty traits, and varieties resistant to nonselective herbicides.
Recently, the focus has been on selecting for soybean herbicide programs. However, it is important to consider characteristics that maximize yield and profitability, as well as your herbicide program.
Soybean characteristics to consider in selecting a variety include maturity, yield potential, disease and pest resistance, iron deficiency tolerance (chlorosis), lodging score, height, and specific soybean quality traits such as protein and oil content.
Selecting soybean varieties that have resistance or tolerance to pests and diseases is an effective and economical method of control. If a field has a history of a particular disease or pest, a resistant variety should be selected that target those specific problems. Many high-yielding varieties have good resistance or tolerance to most of the major diseases in Iowa, such as sudden death syndrome (SDS), brown stem rot, Phytophthora, and white mold. Resistant varieties also are available for soybean cyst nematode.
Each variety has a maximum yield potential that is genetically determined. This genetic yield potential is realized only when management and environmental conditions are perfect, and such conditions rarely exist. The actual performance of a variety may vary from year to year, even within the same field. When varieties are tested over several years in a range of locations, their performance varies depending on environmental conditions. This is because some varieties are better adapted to a specific environment than others. It is not unusual for one variety to out yield another variety by 15 to 20 bushels or more in the same field.
The most accurate prediction of a variety's performance is a stable yield in many locations over several years. Since many varieties today are sold for only 3 to 5 years, the best approach when selecting a variety is to look at the variety information obtained from the Iowa Crop Performance Test and other state performance tests that are replicated in numerous locations.
Planting high-quality seed is essential to a profitable production system. High-quality seed has high varietal purity, high germination, uniform size, no weed seed or green immature seed, no seed coat cracking, no disease or discoloration from fungal or viral pathogens, and no splits. Certified seed meets these requirements.
Some growers save their own seed for planting, which is fine if high quality is maintained and if the seed quality is known before planting. Use only seed produced the previous crop year. Seed two years old or older usually has a lower germination rate.
Information on specific soybean varieties
Information on specific varieties can be found at the Iowa Crop Improvement Association crop performance evaluation program and from individual seed companies.
A fact sheet is availabe to download (pdf file) on variety selection.