The equilibrium moisture content (EMC) of air can be used to predict how the ambient air used for natural air drying (NAD) will affect the moisture content of grain. The EMC of the air depends on its temperature and relative humidity (RH) as well as the grain type. The EMC represents the moisture content that the grain will eventually equilibrate to if the air conditions remain constant for a length of time. Although air conditions are rarely constant for longer than an hour, the EMC information can still be used to determine the range of air temperatures and relative humidities that will achieve drying.
Refer to additional resources at http://pami.ca/crops/storage/ for how to use EMC to manage in-bin grain drying.

These charts are based on the moisture isotherm data summarized in the ASABE Standard D245.5 (Moisture Relationships of Plant-based Agricultural Products) and various published studies (listed after the charts). These charts use the modified Henderson model for flax, peas and canola, the modified Chung-Pfost model for flax, oats, hard red spring wheat and barley, the modified Halsey equation for red lentils, soybeans and sunflowers, and the modified Oswin model for lentils, durum and oats. Note that much of the information in ASABE Standard D245.5 is based on research conducted in the 1980’s and 1990’s. Since that time, plant breeding has resulted in different starch and oil contents of grains and oilseeds which may affect the EMC values. Therefore, the EMC values given should be used as a guideline only.