The ability to store harvested canola and sunflower without any quality deterioration is critical to farmers’ operations.
If you looked up grain storage expert in the dictionary you would most certainly find a photo of Dr. Kenneth Hellevang, NDSU Extension Engineer and Professor. He has provided information on storing sunflowers in previous editions and he says the mechanics with canola storage are similar to sunflower.
Hellevang stresses that what’s important to remember is all grain drying fundamentals apply, no matter what method is being used to dry the grain. These fundamentals can be found in the NDSU Extension Service Publications written by Hellevang.
There are several important differences between drying sunflowers and other grains growers should understand, he says. The biggest being the grain’s weight. “Sunflowers weigh less per bushel, so if you’re accustomed to drying a heavier crop like corn or wheat, you’ll find sunflowers dry quicker because there are less pounds of water that need to be removed.”
In addition, canola and sunflower can be more volatile in storage than other grains grown due to the high oil content in the seeds. As a result, extra care must be taken to properly condition it in order to maintain quality.
Recommended Moisture Content
Oilseeds must be stored at 8% moisture or lower, says Hellevang. “The 8% is associated with a 40% oil content of the seed. Now, we’re seeing oil contents closer to 45%, which is good from a marketing and oil production standpoint, but it also means the storage moisture content needs to be lower – somewhere between 7 and 8%,” he explains.
Growers could also focus on managing stored grain temperatures by cooling grain in the fall and winter. In northern regions, Hellevang says to bring grain temperatures down to just below freezing, roughly 30°F (-1°C). In southern climates, a realistic goal is 40°F (4.4°C) or cooler. For storing grain through warmer temperatures, such as the following summer, the target is to keep the grain as cool as possible, says Hellevang.
The stored grain temperature increases in the spring not only due to an increase in outdoor temperatures but also due to solar heat gain on the bin. Solar energy produces more than twice as much heat gain on the south wall of a bin in early spring as it does during the summer. Hellevang recommends periodically running aeration fans to keep the grain temperature near or below 30°F until the grain is dried if it exceeds recommended storage moisture contents, and below 40°F as long as possible during spring and early summer if it is dry.
Recommended Airflow Rates
Sunflowers – natural air-drying for oil sunflowers requires an airflow rate of 0.75 cfm/bu for up to 15% moisture. The drying should start when outdoor temperatures average about 40°F, says Hellevang.
Canola – farmers need to limit the temperatures as the moisture content increases.
Natural air-drying works well if you are doing it in September or October, but as we get late fall, early winter, the moisture holding capacity of the air is going to be gone, says Hellevang.