LONDON — Multiple factors cause soybean yield gaps and studies show that the most significant factor for Ohio farms is the planting date.
Soybean yield gap research shows that soil fertility, insects, weeds and diseases all cause yield gaps, according to Dr. Laura Lindsey, Department of Horticulture & Crop Science, The Ohio State University. She conducts Ohio farm research in the Benchmarking Soybean Production Systems in the North Central U.S.
“The overarching goal of this research is to identify the yield gap,” said Dr. Lindsey. The yield gap is the difference between the yield potential and the actual farm yield. Yield potential is determined by the environment, such as weather, light, rainfall, soil and other factors.
Dr. Lindsey spoke Jan. 12 to farmers from Madison, Union and Delaware counties at the 2018 Farmer’s Breakfast in London, focusing her presentation on Ohio region data, which is primarily regions 1 and 2. Ohio is a collaborator on the project, led by researchers in Nebraska and Wisconsin.
“For these first two years of the project [2014 and 2015] … here in region 2, averaged across two years, the yield gap was 15 percent,” said Dr. Lindsey. She says that basically means that farmers are missing out on 15 percent of yields. Region 1, across the northern part of Ohio, the yield gap was 26 percent.
Starting in 2014, the study’s researchers surveyed more than 6,000 soybean fields across the region through a paper survey. They then put each field location into TEDS (Technology Extrapolation Domains), which Dr. Lindsey says is basically the environment, based on aspects such as degree days, water temperature and limitations.
They are now in their third year of the project, with two years of data summarized.
“We can actually calculate yield potential for each one of these regions,” said Dr. Lindsey, which she says was estimated using weather data. The actual yield data that farmers submitted was then compared to the yield potential to obtain the yield gap.
What factors are attributed to that yield gap?
The number one factor affecting yield which rose to the surface was planting date in almost all of the regions. The other factors she focused on were foliar fungicide/insecticide, tillage and drainage.
The survey asked farmers for planting date and actual yield information. A farmer at the event asked: So, what’s too early?
“Too early is going to depend on the year,” said Dr. Lindsey. “The first half of May is ideal if it’s doable.” But ultimately, the best time to plant will depend on the year.
The study showed that artificially drained fields yielded higher, versus those without drainage. However, Dr. Lindsey says that it was only significant for region 2 and was less than seven bushels per acre.
Tillage was also significant for region 2. “There are a lot of reasons why you may not want to till, in terms of organic matter or soil health and other factors,” said Dr. Lindsey. “But looking at our data tilled fields tended to yield slightly greater, maybe three or four bushels per acre.”
Foliar fungicide/insecticide was not significant in Ohio, although it was for many other regions. “For Ohio, there was no regional yield response overall with foliar fungicide/insecticide,” said Dr. Lindsey, who added that Ohio does see yield response, but “it’s just not every year, every time it’s applied.”
She added that from their small plot research, “If you have high yielding conditions, good rainfall in June and July, but not flooded, you’re more likely to see a response there to fungicide,” said Dr. Lindsey. In the study, four out of 12 locations had a significant yield increase in fungicide application by four to seven bushels per acre.
She said that there was no yield significant yield increase insecticide application in several locations.
The longer title of this research is Benchmarking Soybean Production Systems in the North Central USA. It is a multi-state project and includes every state in the North Central region, except for South Dakota and Missouri.
The purpose of this research is to evaluate soybean varieties for yield and other agronomic characteristics. This evaluation gives soybean producers comparative information for selecting the best varieties for their unique production systems. For more information visit: www.stepupsoy.osu.edu.
Amanda Rockhold is a staff writer for Rural Life Today. She can be reached at 740-852-1616, ext. 1617.