With the late start and wet “feet” early on, the soybean crop wasn’t pretty going into early August, but the old adage that soybeans are “made” in August came to fruition this year once the weather settled down.
Entering the final 2015 yield estimates that were released recently, the U.S. Department of Agriculture had penciled in a 48.3 bushels per acre national average, up 0.8 from last year.
Emerson Nafziger, University of Illinois crop sciences professor and Extension agronomist, sliced and diced this past growing season in an Illinois Soybean Association-hosted webinar.
“It was a surprising season. Back in August or so, I figured we probably wouldn’t be talking about this with the excitement that we are this year. But the big questions on this crop and many farmers I’ve talked to have had the same question is where did this yield come from,” he said.
Nafziger recapped the weather in Illinois during the growing season, as well as various findings in the university’s soybean trials throughout the state as part of its variety testing program.
Parts of the state had above normal rainfall in May, with a portion of the eastern edge below normal, and temperatures slightly above normal.
“Our soybean crop was largely established by the end of May,” Nafziger said.
Maps of the June rainfall in the state were soaked in shades of above average blue after 10 consecutive days of rain in many parts. Total rainfall was nine inches above average in June, setting a record.
“High June rainfall is generally considered a negative thing for both corn and soybean yields, probably corn a little bit more than soybeans, and we certainly saw that,” Nafziger said.
“The northeastern part of the state got particularly heavy rainfall, and it didn’t go away in June and continued into July in some places. With the flat wet soils that are there, it really was devastating to the corn crop and damaged the soybean crop.
“What we’re seeing I think though is that soybeans were able to come back from that. It wasn’t as far along as corn, and it was generally able to withstand that and not get killed in most places like a lot of the corn crop that was either killed or might as well have been because it never could set an ear and so on.
“It simply might have been the luck of having soybeans planted a little bit later and not to a stage where standing water was going to kill it outright. The remarkable thing is that the soybean crop came along and did what it did after looking pretty poorly by the end of June — both corn and soybeans in the very wet areas.”
Typical Growing Degree Days
Temperatures were around normal in June and slightly below normal in July, but the growing degree day accumulations were typical.
Rainfall was variable across the state in July, with some areas four to six inches above normal.
“July was very mixed with some serious further damage added in some places, but not over a huge amount of the state. A lot of the state dried out to some extent in July and temperatures were moderate. It turned out to be a good month. We had good seed set in corn and good start to the flowering pod-setting process in soybeans,” Nafziger said.
Rainfall in August was below normal in most of the state.
“In fact, toward the end of August, the rain had kind of shut off and we were getting a little bit concerned about the effect of dryness on the crop as it was finishing the seed-filling process,” Nafziger said.
“The temperature helped us out some. Cooler than normal August weather is almost always a benefit for the crops, and that probably proved to be the case, as well. Our high temperatures were around the Farm Progress Show the first part of September. I think the first 10 days of September were probably warmer than any of the 10-day periods in August.
“We were getting a little concerned as August drew to a close. We were starting to see soybean leaves turning and some cause for concern that it was too early for this crop to be finishing up, and there were a lot of pleasant surprises once the leaves fell off and we saw the pod numbers that were there.”
Nafziger’s key takeaways from this year’s soybean crop and variety testing included:
* The rotation trend has been moving back to the more normal 50-50 corn/soybean rotation.
* The corn-to-soybeans yield ratio has been running as much as 3.5 to 4 to 1, but in the last five or six years it has dropped below 3.5; in 2015 it dropped to 3 to 1 — 168 bushels per acre corn/58 bushels soybeans — which makes soybeans more profitable.
* The more than nine inches of rain in June had more of a negative impact on corn than soybeans, which were able to recover and compensate. Many soybean plants were not at a stage where standing water would have killed them, so yields were still fairly normal at harvest.
* No-till fields did not generate as high yields which is not out of line with longer-term tillage trends, but was larger than normal in 2015. It’s important to recognize that no-till soybeans just had some bad luck in some areas, and that’s not likely to repeat. So I wouldn’t be buying a piece of tillage equipment if I thought that’s what I needed.
* Soybean yield is highest when following more than one year of corn. If you plant soybeans in a field that had soybeans before, expect a 5 percent lower yield when planting soybeans after soybeans.
* This was one of those years that it didn’t matter what the maturity was.
* 15-inch rows out-yielded 30-inch rows.
* Optimal yield was achieved when planted from mid-April to mid-May.
* Supplemental nitrogen had a larger impact than usual in 2015.
* Diseases and insects were not prevalent during the growing season.
* Seeding rates to produce stands of 100,000 to 120,000 were often enough.
(Source – http://agrinews-pubs.com/Content/News/Markets/Article/Soybean-yields-rallied-despite-early-outlook-/8/26/14058)