Soybean growers know that to make the most profits they need to keep input costs down and plant varieties that yield well. To aid in their planning for the coming crop season, the University of Kentucky College of Agriculture has information available to assist farmers in variety selection and seeding rates.
A survey in the Kentucky Agricultural Statistics and Annual Report for 2006-2007 showed that while Kentucky producers grow many of the top yielding varieties, they do not always pick the highest yielding ones. This is costing them valuable returns.
In fact, the most used variety in 2007 produced an average of 5.4 bushels per acre less when compared to the best yielding varieties in 2005-2007. This means if producers sell soybeans for $9 a bushel, those that planted the most used variety would be out nearly $50 an acre.
To help farmers know which varieties are the best yielding in Kentucky, UK annually conducts the Kentucky Soybean Performance Tests. These tests include yield data on many of the top selling varieties of soybeans that are grown in several locations across the state. In these tests, all varieties were managed the same way.
"Farmers are looking for data to predict this year's performances, and the best way to do this is to look at a variety's yield data over several years that is grown in several different locations," said Chad Lee, UK grain crops Extension specialist. "The variety trials are non-biased and evaluate numerous varieties across the state making it easier for farmers to compare one variety to another."
Once a variety is chosen, knowing the proper seeding rate can help producers save money on input costs. Many Kentucky soybean growers over-seed to maximize their yield potential, but with rising input costs, this may be one area where they can cut back. The number of established plants needed to produce the best yield is around 100,000 plants per acre for full-season soybeans.
"If they are over-seeding, knowing the proper seeding rates could help them save money without sacrificing yield," Lee said.
When calculating seed costs, producers need to know the germination rate of their seed and the expected stand loss, which is the percentage of plants that do not emerge from the ground, for each field. Stand losses vary depending on the type of field and planting conditions.
Producers who plant in good conditions and in fields with a history of good emergence may only have a stand loss of 5 percent. However, those who plant in cool weather or in fields that stay wet in the spring or contain hard soil surfaces (crusting) may want to estimate their expected stand loss at around 30 percent.
A table containing several seeding rate calculations can be found in the "UK Corn and Soybean Newsletter" for December on the UK grain crops Extension Web site at http://www.uky.edu/Ag/GrainCrops/. The Kentucky Soybean Performance Tests and the Kentucky Corn Hybrid Performance Test also can be found on the Web site.
Both are also available at county offices of the Cooperative Extension Service.