Predictability Power

BY LAUREN HOUSKA

When it comes time to purchase seeds for next year’s growing season, weighing the pros and cons of the hundreds of available soybean varieties can be overwhelming.

“Seed selection in soybean production is key to maximizing yield potential and has a large impact on profitability,” says Scott Nelson, Iowa Soybean Association (ISA) On-Farm Network® director. “It’s one of the most important management decisions farmers make each year.”

With rising production costs and depressed soybean prices, risk management is paramount. In addition to selecting seed varieties that will produce high yields, farmers need to choose the right mix of varieties to minimize the risk of any individual variety.

“It’s estimated soybean yields increase annually by about one-third of a bushel per acre due to genetic improvement,” Nelson says.

While some new varieties may show this response, Nelson cautions, others may not yield any better than a variety currently being used. Consulting all reliable resources available will aid in the decision-making process.

Farmers often have a handful of these go-to sources of information.

For Tom Oswald, a Cherokee County soybean farmer, those sources include his personal experience, seed company data, information from networking with other farmers and the Iowa Crop Performance Tests.

The Iowa Crop Improvement Association (ICIA), an Iowa State University (ISU) affiliated nonprofit founded in 1902, conducts and publishes results from the Iowa Crop Performance Tests each year, funded in part by an investment from ISA. The data has provided direct comparisons among a large number of soybean varieties in many different environments for over 50 years. The association will mark its 100th year of corn testing in 2019.

“I’ve been looking at the ISU data since I started farming,” Oswald, a long-time ISA member, says. “I like the unbiased nature of the report. I think it is a very important piece of information to compare across companies and varieties.”

ICIA Executive Director Jim Rouse says there are two distinct ways to look at yield data, depending on the end goal:

1. To understand — Look at environmental factors like weather, soil type, management practices, etc., which led to a certain variety’s success or failure that growing season.

2. To predict — Look for indicators that a certain variety will succeed with your operation, despite or in combination with the aforementioned environmental factors.Rouse reminds farmers to carefully consider the various combinations of maturities and defensive and offensive traits that are important to them in addition to high yields and yield stability.

“Remember, variety selection for the upcoming year is not about identifying which lines did best over the past year — it is about predicting which lines will do best in the future,” Rouse says.

Jim Rouse, Iowa Crop Improvement Association executive director, examines soybeans in a field near Ames.

While the specifics of the seed selection process may be unique for each farmer, both Rouse and Nelson offer similar advice for utilizing yield trial data to make predictive decisions:

• Yield trials do not have to be performed on your farm or under conditions exactly like your field to provide relevant data.

• Data from multiple locations should be used to make predictive selection decisions.

• To avoid getting hung up on insignificant differences, use the least significant difference (LSD) to help you sort entries.

• Make initial selections based on yield and appropriate maturity.

• Once you have a pool of contenders, sort among these to identify lines that have the desired mix of defensive traits and make sense for your operation.

Oswald employs a similar approach, identifying candidates in his desired maturity zone first.

“Among those candidates, some varieties may look really good at first,” Oswald explains. “But as I take a closer look to narrow down candidates, it becomes clear some won’t fit my exact needs.”

Oswald then sorts the outstanding candidates to identify lines that have defensive traits important to his operation. Resistance to certain diseases, like white mold, are big factors. As a farmer using no-till across soybeans and strip-till on corn, Oswald is also particularly interested in new varieties that could improve weed management.

Trustworthy year-over-year data across multiple locations and varying conditions is hard for farmers to find, says Oswald. If more companies entered the ISU trials each year, the data could be even more useful for farmers making predictive decisions.

“Farmers can make better decisions — and have peace of mind — when we have access to more information.”

Contact Lauren Houska at lhouska@iasoybeans.com.