Fertilizers, fungicides and insecticides can help improve soybean yields, but stacking on every available input might not be the best plan. To help farmers determine what input investments are most likely to pay off, Ohio State University Extension researchers have been comparing yield responses and costs with various combinations of inputs.
• On-farm research puts crop input recommendations to the test.
• Soybean project compares responses to fertilizers, fungicides and insecticides.
• Crop rotation project shows differences in profitability.
“We really just made the laundry list of everything we could apply to soybeans,” says John Yost, OSU Extension educator in Fayette County. During the 2008 crop year, he worked with local farmer cooperators to set up on-farm studies to evaluate soybean inputs. Then in 2009, he continued the study at the Fayette County Research Farm. Other members of the Extension Crops Team also conducted similar studies in 2009 in Wood, Fulton, Delaware and Defiance counties.
At each of the sites, treatments were a little different, depending on local production practices and circumstances, Yost explains. However, each of the research projects evaluated yield differences as additional inputs were added. They also looked at the cost of each treatment to determine how much of a yield increase would be needed to pay for the treatment.
Overall, Yost says, the results have added support for research done in the past, but it’s too soon to get a full picture of the yield differences. For instance, he explains, weather conditions during the growing season last year limited the development of several diseases that have caused significant yield losses other years. As a result, last year’s study showed that applying fungicides didn’t significantly improve yields.
“We didn’t have the environmental pressure to see diseases this year,” he explains. Since fungicide application costs $20 to $30 an acre, the yield difference must be 2 to 3 bushels per acre just to pay for the application, he adds. So applying fungicide actually reduced net returns.
Even so, years with different weather could show different results. “This needs to be continued so we can come up with the odds,” Yost suggests. “Without long-range weather forecasts, it’s always going to be a gamble applying some products.” With some products, farmers can scout and react to what they find, he notes. But other products can’t wait for scouting to show a problem developing.
“With some products you can do a thorough scouting job and can be reactionary, but with others you have to be visionary,” Yost notes.
In addition to fungicides, the study looked at the response from applying insecticide. Last year just one of the research sites, Wood County, showed a statistically significant response. Other sites showed a 1- or 2-bushel advantage, but that wasn’t enough to be statistically significant. “Those were probably break-even situations,” Yost says.
As each additional input was added, production costs stair-stepped upward, Yost points out. But net returns didn’t step up to keep pace. He intends to continue the study in the coming year by comparing differences in yield and net return with 10 different inputs, including fungicides, insecticides and foliar fertilizers. However, instead of stacking treatments, he’ll test each input individually.
While new corn and soybean genetics have steadily increased yield expectations, farmers are still depending on the Tri-State Fertility Recommendations based on older genetics. To see if the recommendations still hold true, OSU Extension researchers have been testing yields at different fertility levels as well as comparing yields from different crop rotations.
“That work to date has shown we’re still where we should be,” says Yost.
He has been working on the research with Robert Mullen, nutrient management and soil fertility specialist with OSU Extension, and Ed Lentz, OSU Extension educator in Seneca County. The study compares three different crop rotations: corn-soybean, continuous corn, and two years of corn followed by one year of soybeans. 2009 was the fourth year of the ongoing study.
Even though yields are higher than when the fertility recommendations were written, the crop removal values for phosphorus and potassium have stayed the same, Yost notes.
For instance, according to the recommendations, 1 bushel of corn removes 0.37 pound of phosphorus and 0.27 pound of potassium. The field research compared two different fertility levels: The first rate was based on those crop removal values and the second rate was double the crop removal values. The higher rate showed no yield advantage. The researchers also will look at soil test values, but it is too soon to determine if there have been changes over time, adds Yost.
Another aspect of the research compared the profitability of the different crop rotations using current market prices and yields.
At the Fayette County test site, the corn-corn-soybean rotation was the most profitable over the past four years, with an average net return of $285 per acre. The corn-soybean rotation averaged $278 per acre, but the difference between those two rotations was not statistically significant. However, the continuous corn system was significantly less profitable, at an average of $200 per acre over four years.
Yost was originally interested in seeing how continuous corn would compare because he anticipated increased demand from the local ethanol plant. However, over the past several years soybean prices have been relatively higher, so there is now more local interest in raising continuous soybeans than continuous corn. To find how those production systems compare, the range of rotations in the study is being expanded to include continuous soybeans.
Keck writes from Raymond.
For more about these studies and other research by the OSU Extension Crops Team, refer to the research section online at agcrops.osu.edu.