As if soybean growers didn't already have enough trouble trying to secure a good yield this year, many of them are now being faced with a couple of harvesting challenges, according to Extension Service agronomist and soybean specialist Shawn Conley.
Reports from southwest Wisconsin, the Extension Service's research plots near Lancaster, and parts of adjacent states where the soybeans have already matured, whether drought induced or not, indicate that shattering of the upper pods is occurring, Conley noted in a recent advisory.
Conley agrees with Extension Service colleagues from Illinois and Minnesota that pre-harvest shatter frequently occurs with early-maturing soybeans such as those that were at the R7 maturity stage before rains fell in early September.
According to Emerson Nafziger of the University of Illinois, it was too late for those soybeans to add any more weight to their grain but the beans probably swelled several times due to the rain and several recent mornings of heavy dew.
Due to the drought during much of the growing season for the soybeans, the pods developed weak sutures, Nafziger explained. With the rewetting of the pods and possibly the beans, the pods open more easily as they dry again, he observed.
Conley's second but perhaps less plausible hypothesis is that the shattering is linked to the natural tendency of soybeans and all other plants to disperse their seed and thereby survive and reproduce.
He surmises that in this case the early shattering might be drought-induced but he also realizes that soybean breeders have taken out much of the natural tendency to shatter.
Regardless of why shattering occurs, the obvious concern is the loss of yield, especially with a crop now worth as much as $16 per bushel, Conley remarked. He pointed out that the loss of four seeds per square foot converts to a yield loss of about one bushel per acre.
In addition to the potential of shatter loss, many soybean growers are plagued with fields that are varying greatly in maturity because of difference in soil types and a combination of knolls with flatter landscapes, Conley stated in a separate advisory late last week.
The prevailing question is what to do about harvesting when some of the soybeans are already down to a 13 or lower percent moisture while other parts of the field still have green seed, Conley observed.
Deciding what to do is complicated by the fact that the higher yields are probably concentrated in the soybeans with the green seed, he added.
Conley's guidelines on how to resolve this dilemma are headed by the suggestion of harvesting the field at different times, perhaps at intervals of two weeks or more, if this is practical.
But he concedes that this isn't easy with large equipment that needs to be moved between fields and for growers who own or rent land over a fairly large geographical area.
Second on Conley's guideline list is waiting until the entire field is ready for harvest with ripe soybeans.
In some cases, this would require accepting yield losses due to shattering but it would probably be the best decision if there is no shattering or it does not become severe, he indicated. At the same time, he noted, no premium is paid for soybeans at below 13 percent moisture.
If shattering is the primary concern, harvesting as soon as possible is "the next logical approach" but it will create the problem of having wet and immature seed, and probably more foreign matter, in the mix, Conley warned.
As with soybeans that freeze before maturity, the subsequent problems will include low test weights, heating, shrinkage, and discounts at the elevator, he indicated.
Beyond this, many combines have trouble handling immature soybeans, Conley stated.
He said the still green pods would either end up in the grain tank as unthreshed soybeans or on the ground in the field and pointed out that growers should know which of these scenarios is likely with the combine they will be using.
Whatever the situation, growers need to calculate the bottom line on how to make the most dollars from their soybean crop, Conley concluded.
He leans toward harvesting a crop that is overly dry rather than incurring significant dockage but adds that growers need to decide on which yield environment to protect by how they focus their time and efforts.