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The effect of environmental variables such as temperature, relative humidity, rainfall,
sunlight and wind movement on the storability of grain in silos cannot be over emphasized. An
evaluation of environmental variables on stored grain inside a portable steel silo was carried out to
determine its optimum working condition in a humid tropical environment of Ondo State, Nigeria.
Parameters such as internal silo temperature, ambient temperature, ambient relative humidity and
grain moisture content were measured in six months (October 2013 - April 2014). Internal silo
temperature was measured at six hours interval using thermocouples and a data logger of model
TC-800D. The ambient temperature was measured using a digital thermometer. A digital hygrometer
was used to measure ambient relative humidity. Moisture meter was used to measure the grain
moisture content. The data collected over the storage period of 24 weeks were subjected to appropriate
statistical analysis using SPSS version 21.0 and Microsoft excel. The results showed that the
internal temperature ranged from 20.20C to 39.00C while the ambient temperature ranged from
20.00C to 34.20C. The minimum moisture content of grain was 11.5% (wb) and the maximum
moisture content was 13.9% (wb) giving an increment of 2.4%. The highest values of grain.
moisture and temperature were obtained at the grains stored at the topmost part of the silo. Moisture
migration occurred within the grains from the silo wall to the centre of the silo. The ambient relative
humidity ranged from 74% to 93%.lt is advised that the grain loaded into this silo should be of
moisture content between 11.5% (wb) to 13.9% (wb) to prevent moisture migration and to enhance
storability. It is recommended that the silo should always be placed under shed to avoid rain and
direct sun.
Key words: Storability, Steel silo, Moisture content, Temperature, Relative humidity