Physical changes in large-scale hermetic grain storage

Abstract Moisture content (m.c.) and temperature were measured in two 1300 t semi-underground hermetic concrete silos filled with maize which was stored for nearly three years in an upland equatorial climate. Gradual cooling of the maize took place in the first year of storage and the temperature remained constant thereafter. This could be explained by calculations of the effects of heat loss by conduction and air convection and heat gain through grain respiration. Considerable m.c. increases occurred at the maize top surface and calculations indicate that this was mainly due to air convection currents at night when the silo structure above ground was cool compared with the grain interior.