With varying moisture levels at harvest this year, growers should spend a significant portion of their time monitoring stored grain.
Whether the grain has been run dry or at higher moisture levels, tracking that grain after storage is just as important. Much of this crop’s grain was harvested in warm temperatures, creating ideal conditions for condensation when outside temperatures drop to 40 degrees and below. More stored grain deteriorates because temperatures are not controlled than for some other reason.
Air must be added to the silo in order to cool the grain evenly throughout the silo. Areas with the greatest risk of condensation damage are at the top center of the bin and along the sides of the bin.
Whether harvesting dry cereals or cereals with higher moisture levels, there are some key moisture thresholds to keep in mind when setting up cereals for storage at longer term.
For corn that will be moved in six months or less, grain moisture levels should be 15.5%. If this corn is to be stored for six to 12 months, it should contain 14% moisture. Soybeans that will be sold before spring should contain 14% moisture or less in the bin. Soybeans that can be stored for up to a year must contain 13% moisture before being placed in the bin.
Additionally, soybean seed quality could be an issue this fall. Much like in early fall 2018, excessive rains in late September and early October can be more than many early-planted soybean plants can withstand.
The wet weather occurred as some soybeans were at or near physiological maturity. The entire factory was starting to shut down as their seed-making mission was over. The humid weather provided the perfect conditions for various fungi to take advantage of these plants. In addition, these conditions promote germination while the seeds are still in the pods.
This humid weather also provided the perfect environment for saprophytic fungi to colonize soybean plants and phytopathogenic fungi to colonize stems and pods and infect seeds. The most notable are the pathogens that cause Phomopsis seed rot and seed purple spot. Phomopsis seed rot is particularly known to reduce seed germination and Phomopsis and purple seed colouration may reduce other quality measures, such as oil and protein concentrations.
The main way to deal with Phomopsis seed rot and seed purple colouration is to harvest soybean fields as soon as possible after they mature. When heavy rainfall occurs after soybean ripens, the risk of these seed diseases increases dramatically.
The fungi that cause these diseases during the winter on soybean residues in fields and can be transmitted by seeds. Therefore, rotating crops and avoiding sowing seed in a hopper can also help reduce the risk of these diseases. Fungicides applied to foliage may have some effect on these diseases and protection against these diseases may increase slightly if applied at the R5 growth stage (early seed stage). However, when high amounts of frequent precipitation occur after fields have matured, the effectiveness of these management practices may be limited.
Germination of seeds in the pod is a rare event. First, soybeans should dry below about 55% humidity at which the seeds reach physiological maturity. Second, seeds that were below about 55% humidity must soak in enough water to come back above 55% humidity for the seeds to germinate. This order of events is extremely rare on upright soybean plants where the pods are exposed to air and sunlight as the leaves fall.
Drying and wetting the soybean pods weakens the pods. As the pods dry a second or third time, many pods split open and drop seeds to the surface of the soil.
Farmers can expect lower yields and damaged seeds. Damaged seeds are likely to benefit from reduced prices from grain buyers. Farmers who have drying capacity could try harvesting soybean fields as soon as field conditions and machine performance permit.
The wet weather in late summer was a blessing for crop growth and higher yields. The wet weather when soybeans ripen can be a curse on seed quality and yields.
For more information on grain storage, contact the Hardin County Extension Office at 765-4121.