Harvest has begun, which means farmers are spending more time in their combines and have their eye on their yield monitors.

Every year, farmers will undoubtedly find parts of fields that yield less than others, and some might wonder what they can do to fix it.

The soy checkoff funds research to increase and protect soybean yields. One example is a project led by Shawn Conley, Ph.D., extension soybean specialist at the University of Wisconsin.

“I’ve been working on the USB High Yield Project, and have been asked many times why we’re conducting this type of high-yield research,” explains Conley. “First, we want to understand the yield potential out there for growers. Our point is trying to understand the factors that cause the biggest yield loss and strategies that will give farmers a positive return on investment to increase soybean yields.”

Common yield-limiting factors include:

1. Soil quality, such as texture, type, structure, nutrient availability and pH.

2. Excess moisture.

3. Stresses, such as diseases, insects and weeds.

4. Field history, including herbicide, pesticide and fertilizer applications.

Conley suggests the following three management strategies to ensure maximum soybean yields and urges farmers to see them as investments, not expenses.

1. Genetics. To ensure maximum yield potential, farmers should select the best genetics and traits. According to Conley’s data, farmers could see as much as a 20-bushel difference between the best- and worst-yielding varieties in a trial location. He encourages farmers to ignore early sales and wait for yield data from the previous year before making seed-selection decisions.

2. Pre-emergence herbicides. At minimum, these inputsmaintain yield and, in many cases, improve it. They also allow for greater flexibility of post-emergence herbicides and reduce early-season competition between weeds and the crop. “Looking across the United States, the prevalence of herbicide-resistant weeds is moving northward,” says Conley. “If you want to look for problems, go to those areas focused on glyphosate for the last 10 years, and you’ll see the kind of train wreck you want to avoid.

3. Fertility. Inadequate soil fertility is one of the main yield-limiting factors over the last two decades, Conley says. The levels of potassium and phosphorus in the soil have steadily dropped throughout the Midwest. As yields have improved, so have the amounts of these nutrients that those crops have removed. Maintaining fertility is important for optimizing yields on both a short-term and a long-term basis. Soil testing is the best guide to soil fertility. Conley urges farmers to take soil tests and use the results to build a customized nutrient-management plan that will improve yields throughout all fields.