Is dry soybean seed an issue for 2012?
Areas of Iowa and other Corn Belt states were very dry during soybean harvest in 2011. Subsequently much of the soybean harvest occurred at lower than normal grain moisture levels, including soybeans grown for seed. We have heard reports from farmers, Extension and industry personnel that some fields were harvested with seed moisture as low as 7 percent. Handling seed with low moisture must be done very carefully to prevent damage to seed coats. This includes seed movement during harvest, seed cleaning, seed treatment and delivery to planters.
At this time it is not possible to prevent damage done during harvest, and typically farmers, elevator operators and seed dealers handle seed as carefully as possible to prevent postharvest damage. Careful movement of seed includes avoiding use of steel screw augers, slower than normal flow rates whether with air, conveyer belt or brush augers, and keeping seed drops as short as possible to prevent damaging soybean seed coats. When handling individual bags of soybeans, simply dropping them onto one another off the back of a truck may damage soybean seed coats. This is even more of a concern this spring given the very dry soybean seed from the fall of the 2011 harvest. Seed with damaged coats rarely contribute to stands.
Farmers should carefully read tags or papers obtained with each seed lot purchased. Information on Certified Seed tags or Quality Assurance papers will include germination percentage. It is important that farmers use the Pure Live Seed percentage when determining the desired seeding rate. But remember, the germination on tags or papers was the germination when the seed left the point of purchase. Soybean seed often is moved at least two times prior to planting, and each movement can result in decreased germination. However, germination percentage does not always tell the entire story on vigor of seed, particularly for soybean seed.
Seed Germination Tests
The Iowa State University Seed Testing Laboratory offers several tests that can provide additional, useful information for farmers. These include Sand Germination (7-10 days duration), Cold Germination (Iowa Test, 12-14 days duration), and Accelerated Aging (about 10 days duration). Results from these tests can help determine seeding rates required for each specific seed lot, a particularly important consideration for early planting soybean. Additional information on seed testing by the ISU Seed Testing Laboratory is available at: http://www.seeds.iastate.edu/seedtest/