As of this week, about 60% of our soybean crop has begun dropping leaves, a good sign of full maturity and harvest in the near future. As of Oct. 25, about 10% of the soybean crop has already been harvested. As we progress into harvest a few things to keep in mind are as follows:
When harvest is delayed due to bad weather, or when some varieties dry down to seed moisture levels below 11%, seed shattering may occur in the field or at the cutter bar at harvest. To reduce the potential for shattering losses, harvest should begin at seed moisture levels of 14% to 12%.
If storage bins have the capacity for drying with air blowers, harvesting at 16% is not out of the question. In fact, for most years in South Carolina, those farmers who wait for ideal moisture around 12% often have difficulty harvesting their entire crop without losses in yield and quality, either from shattering, lodging or disease.
Timely harvest is essential in obtaining maximum yield and a high-quality crop. Significantly reduced yield and quality may be expected if harvest of maturity group IV is delayed due to unfavorable weather conditions.
As we begin winding down the growing season termination of insecticides, irrigation, and fungicides are often questioned. Clemson’s recommendation for termination of these products and practices would be to ensure that all insects are below the threshold at the R6 growth stage, to terminate fungicide applications at the R6 growth stage and to terminate irrigation at the R6.5 growth stage.
As a reminder, the R6 growth stage in soybean is when pods are completely filled by seeds on one of the top four nodes. The R6.5 growth stage is when all seed has fully filled a pod in the top four nodes of the plant and the ends of the seed are squared off. At this growth stage seed should come out of the pod somewhat easy.
Soybean drying and storage
Drying and storage are essential components of maintaining soybean quality, and understanding these factors is instrumental in reducing production costs and maximizing returns. In order to minimize seed damage (e.g., breaking and splits) and losses, soybeans should be harvested in the range of 15% to 13%.
But for facilities with drying capabilities, beginning at 16% to 17% is not unreasonable (Hurburgh, 2008). At higher moisture contents, soybeans can be difficult to harvest, but at lower moisture contents, damage can increase.
To reduce quality degradation and provide safe long-term storage, it is important to cool and dry the grain quickly after harvest. The desired final moisture content depends on the application. The general soybean market moisture is 13%. If the soybeans are sold directly or stored for a short period, the moisture content should be as close to this value as possible to maximize the weight of soybeans sold while avoiding drying charges (see the discussion of moisture shrink below).
However, storage times are greatly increased at lower moisture contents of 10% to 12%. At temperatures below 40 degrees Fahrenheit, insect activity is greatly reduced. And when the relative humidity in the air space between beans is below 65%, mold growth is significantly reduced.
Conditions that fall below the 65% RH line shown would generally have reduced mold growth. An estimate of the allowable storage time at various temperature and moisture combinations is shown in the table below. For more information on soybean drying and storage refer to the South Carolina Soybean Production Guide.
Clemson University contributed this article.