Recommended Drying Temperature, Air Flow, Seed Depths
When heated air is used for drying, there can be large differences in degree of drying between the layer of seed near the air inlet and top layers. To minimise this difference and to avoid extensive over drying of the bottom layers before the top layers are dry, it is necessary to dry seed at shallow depths in heated air drying. Table gives the recommended maximum seed depths for batch drying in a bin. If the seed is to be stored in the bin where dried , the seed depth could be approximately double that shown in table since, in storage , drying is usually done at lower temperatures than in batch drying.
Recommended Temperatures and Depths for Heated Air Drying of Various Crop Seed in Bins:
Sr.No | Seed | Maximum Depth | Recommended Drying Temperature |
1 | Shelled corn | 20" | 110 0F |
2 | Wheat | 20" | 110 0F |
3 | Barley | 20" | 105 0F |
4 | Oats | 36" | 110 0F |
5 | Rice | 18" | 110 0F |
6 | Soybeans | 20" | 110 0F |
7 | Peanuts | 60" | 90 0F |
8 | Grain Sorghum | 20" | 110 0F |
Heated Air Drying Requires Higher Rates of Air Flow for Two Reasons:
1. Water is evaporated faster and more air is needed to carry it away, and
2. The higher the rate of air flow, the more uniformly there is in the drying of upper and lower layers of seed. Moreover, drying proceeds considerably faster at recommended temperatures at higher rates of air flow. Sometimes the drying time can be halved by doubling the air flow.