Due to the cool and wet conditions, soybeans harvested at this time of the year will need to be dried on the farm or at the elevator. Some elevators will accept soybeans up to 18 percent moisture while others will reject loads that are above 15 percent moisture. Contact your elevator prior to delivery and understand their discount schedule. Information on understanding soybean discount schedules is available in “Understanding soybean discount schedules” from Michigan State University Extension.
Commodity soybeans used for domestic crush or export can be dried using supplemental heat. However, food grade and seed beans should not be dried with supplemental heat. Proper management is essential to minimizing damage when using supplemental heat. Keep the drying temperature below 120 degrees Fahrenheit.
Medium temperature drying as discussed above will damage the seed coats and increase the amount of split beans. Most elevators will begin discounting for split beans when they exceed 20 percent and some elevators may reject loads harvesting more than 20 percent splits. This level of damage may be exceeded when using supplemental heat (Table 1).
However, natural air and low temperature drying are not good options at this time of the year. The amount of damage will vary between soybean varieties and grain drying equipment. Check for cracked seed coats and split beans often and adjust the drying temperature to achieve the level of cracking and splitting that is acceptable to you and your grain buyer.
|Table 1. Drying temperature effects on soybean quality|
|Drying temperature (F)||Seed coats cracked (%)||Split beans (%)|
Source: Ken Hellevang, North Dakota State University Extension Service
Checked or cracked seed coats are not discounted by elevators. However, once the seed coat is damaged, the seed is much more prone to splitting when handled or transported. Again, loads containing more than 20 percent split beans will be discounted and possibly rejected. Producers can use a simple and quick procedure, the hypochlorite test, to identify seed coat damage that is not easily detected by the naked eye.
Simply soak 100 beans in a 20 percent bleach solution for about five minutes. Beans with damaged seed coats will swell and be larger than undamaged beans. Wrinkled seed coats are OK.
Your target moisture content depends on your storage and marketing plans. If you plan to deliver the beans shortly after drying or store them until spring, shoot for 13 percent moisture. If you plan to store the beans on-farm through the summer, dry the beans to 12 percent moisture.
Your best strategy for holding the beans through the winter is to cool the grain mass to 32 to 35 F using the aeration fans. If daytime temperatures are above 35 F, run the fans at night when temperatures fall below 32 F. Ice or frost may occur on bin vents at temperatures near or below freezing, so leave the fill hole or access door open to reduce the potential for damaging the bin roof when operating fans.
Check the temperature of the beans in several locations in each bin every two to three weeks during the winter and more frequently as outside temperatures increase in the spring. Pay particular attention to the south side of the bins in late winter or early spring as the grain temperature along the bin wall will increase more rapidly due to increasing solar energy. Keep grain cool during the spring and summer. Grain temperatures above 50 F increase the potential for insect and mold development.
Careful management when drying and storing soybeans is essential to maximizing farm income.