Minimize soybean harvest loss and maximize cost per bushel
Over the last several years of working with what I consider the top soybean producers in Lebanon County, I have learned the importance of timely harvest of soybeans. This week I noticed late group 2 beans were approaching harvest moisture. It has been my experience that once 95% of the pods turn brown, about a week later it’s time to combine. Some recent work at Iowa State showed a 3.2% loss of moisture per day - more than 5 times that of corn. So dry down is quick. The data also suggested about 12 days after pod maturation 13% moisture was noted over the study period.
Once moistures dip below 13%, a grower is essentially giving the mill soybean dry matter since they will correct the moisture to 13%. I still remember John Yocum referring to the fact that after the plants first reach harvestable moistures dry matter losses occur simply by the alternating day night and heavy dew. Here is a picture of our crop teams’ soybean planting date study (figure 1). Same variety, same seeding rate, same pest management program, the only variable was the date of planting in these plots from March 28th to May 28. It is important to consider the variety since some varieties will have slight differences in the pod integrity and not tend to split as the heavy dew at night can speed up this process. There are also impacts of erect varieties that might tend to dry quickly and delays in harvest may impact those versus varieties that tend to lay over and nestle protecting large fluctuations in dry down. This picture was taken from our Landisville Research Station where I had planted the same variety on 5 different planting dates. The early planting was ready to combine the soybeans on the left (planted two weeks earlier than the beans on the right) could be harvested two weeks before later plantings. If I were to wait as little as two weeks to harvest the plots until the rest of the planting dates matured, I would lose a significant amount of soybeans from shatter losses.
For more details, check out this research from Penn State University.