By Emily Unglesbee
DTN Staff Reporter
ST. LOUIS (DTN) -- Pete Bardole's soybean fields are talking to him, and the central Iowa farmer doesn't like what he's hearing.
"You can just stand there and listen, and you can hear the beans popping across the field," he said. "And that's never a good sound."
Bardole's no-till corn and soybean operation near Jefferson, Iowa, has seen about 15 inches of rain since the first of September, he told DTN. After the latest 1.5- to 2-inch rainfall last week, his soybeans began to voice their displeasure.
"They've just been wet and dry so much, the pods are opening up," he explained.
The risk for in-pod germination will also rise with each fall rainfall, but that phenomenon is very rare, Extension agronomists and educators told DTN. More critically, farmers should begin to adjust harvest schedules and strategies in the face of increasingly fragile beans.
PRIORITIZE SHATTER-PRONE FIELDS
As soybeans swell up after rainfalls or damp nights and then dry down repeatedly, the beans and pods can become more fragile, Iowa State Extension agronomist Mark Johnson explained. Most yield losses happen when fragile plants are jostled by the combine header. Pods pop open and drop their seeds before they can be shuttled into the combine.
In some cases, movements as mild as a breeze can cause the pods to split open, hence Bardole's unprovoked, in-field symphony of pops, University of Illinois Extension educator Dennis Bowman explained.
The wetting and drying cycle can also result in more split and broken beans, Bowman added. For farmers like Bardole, who grow soybeans for seed companies, this might mean a loss of premiums.
As a result, Bardole is making the fields where his beans are audibly shattering a top harvesting priority. "Those fields were still wet, but when I heard them popping, we decided we had to get in to get what we can," he explained. "If we have to come in later and combine wet spots that we had to dodge, we'll do that."
The problem will only get worse as the weeks proceed, Bowman confirmed. "This is kind of a natural characteristic of soybeans to survive when they get to a certain dryness point -- the pods shatter to spread their seeds so they can reproduce."
That dryness point tends to be around 10% moisture content, he said. Farmers can try to harvest overly dry, fragile bean fields when the air is less dry, Johnson said. Early mornings after dew falls or in the evening when the air is cooling down are best. "Avoid the middle part of the day, when the air is driest," he said. "Beans' moisture will fluctuate with the air moisture."
Perfect timing can be tricky for farmers in areas that have seen a lot of rain, Bowman conceded. Farmers will have to balance the need for dry, stable fields with the need to get soybeans out with minimal shatter loss, he said.
The DTN/Progressive Farmer weather forecast calls for the Great Lakes area to have the highest risk of wet-weather concerns through the end of October. Michigan's bean acreage was only 23% harvested on Oct. 20, according to USDA reports.
Bowman said growers will need to experiment with combine settings when harvesting a shatter-prone field. Typically, slower ground speeds and faster real speeds are the answer, but they must be calibrated carefully through trial and error.
VET YOUR VARIETIES
Shatter rates in soybeans will vary from variety to variety, and this year could be a good one to evaluate which soybeans were more shatter-prone, Bowman said.
Most years, farmers can anticipate an average rate of shatter loss around 5%, according to a University of Missouri Extension guide.
In a year like this one, Bardole suspects the shatter loss percentage for some of his fields will get into the teens and make a dent in overall yields. "We got rained out one night, when we partway done with a field," he recalled. "When we went back four to five days later, there was a noticeable drop in yield from before the rain to after."
The Missouri guide establishes a chart for scouting fields for shatter and other types of harvest loss. You can find the guide, which also outlines how to best avoid shatter during harvest, here: http://goo.gl/….
In addition to evaluating the shatter rates in their varieties, farmers may also benefit from "spreading their risk" of shatter by selecting a range of maturities for planting next year, Bowman added.
"A lot of people look at what's going to give the maximum yield and end up with most of their acres in one, two, or three different varieties, all with very similar maturities," he pointed out. "This fall, something they may want to think about is varying their maturities more so they're not all coming into maturity at the same time."
In the meantime, all you can do is check your fields for weakened pods and harvest them as quickly as possible, Bardole concluded.
"The later we get with harvest, the more trouble we're going to have," he said.
Emily Unglesbee can be reached at email@example.com
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