It is important to monitor grain temperature and to keep stored grain cool and dry by regular aeration or by turning it. High moisture and warm temperatures in grain allow for the rapid growth of insects, fungi and the possible production of mycotoxins.
Grain stored at lower temperature has less risk of losing quality:
Grain is a very good insulator. When it is undisturbed, it holds temperature well. If warm grain is placed into storage and left undisturbed, convection currents develop and cause hot spots and moisture condensation. The greater the temperature differential (the difference between the temperature of the grain and the outside temperature), the stronger the convection currents. The stronger the convection, the greater the effect of heating and condensation on the grain. This is particularly evident when stored grain is not levelled and the grain bulk forms a peak.
The cycle of convection currents in bin-stored grain when ambient air outside the bin is cold and the grain is warm.
In the bin:
Arrows in the image represent the convection currents:
During the storage of grain respiration takes place when heat and carbon dioxide are released. The higher the moisture content and temperature, the higher the respiration rate and as a result more and more energy is released. The temperature of the grain can increase so high that heat damage takes place. The only way in which respiration rate can be decreased is to cool the grain by means of aeration.
It is a big dilemma if the build-up of heat is noticed in a bin at a late stage. It can easily happen that the wrong decision is made if an aeration system has not been installed. Corrective steps must then be followed. The following emergency measures can be taken:
If silos are equipped with temperature monitor variables, an increase in temperature can be detected sooner and preventative measure can be implemented sooner.
Check the temperature of the bin every 2 weeks. Measure temperature by using temperature sensing cables that are permanently installed or by probing the grain with an electronic sensor device.