PRESERVATION, ENHANCEMENT, AND MEASUREMENT OF GRAIN QUALITY AND MARKETABILITY
Location: Engineering and Wind Erosion Research Unit
Title: Grain aeration
Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: September 26, 2011
Publication Date: September 1, 2012
Citation: Navarro, S., Noyes, R.T., Casada, M.E., Arthur, F.H. 2012. Grain aeration. In: Hagstrum, D.W., Phillips, T.W., and Cuperus, G., editors. Stored Product Protection. Manhattan, KS: Kansas State University Research and Extension. p.121-134.
Interpretive Summary: Stored-grain aeration uses low airflow rates from fans to condition grain with ambient air. The objective of aeration is to provide favorable conditions to maintain stored grain quality, usually by cooling the grain. Aeration flow rates are much lower than airflow rates with grain drying, so fans sized for aeration cannot normally be used to dry grain since the drying process would be impractically slow with small aeration fans. Conversely, aeration flow rates are much higher than those with recirculated fumigation. Aeration is widely used in stored grain management programs in the United States (U.S.). Aeration technology is used to modify the temperature and humidity in the grain bulk to reduce or eliminate the development of harmful or damaging organisms in the grain, and to prevent moisture migration in the grain bulk, and minimize water condensation on the underside of bin roofs. Condensation under-roof can result if grain remains warm when ambient temperatures are low enough to trigger condensation under the roof and roof venting system designs are inadequate - not enough convection (wind) airflow through the headspace. Aeration is used to lower and maintain grain temperatures at safe levels to prevent insect development and humidity levels below that required to support fungal activity. Thus aeration helps maintain favorable storage conditions for the safe preservation of grain quality.
Aeration, the forced movement of ambient air by fan power through a grain bulk, is widely used in stored grain management programs in the United States (U.S.) to maintain favorable storage conditions for preserving grain quality. Aeration flow rates are lower than rates from grain drying, which uses very high airflow rates, and are higher than from recirculated fumigation, which uses very low airflow rates compared to aeration. Aeration is usually used to cool the grain bulk to reduce or eliminate the development of damaging organisms in the grain, while keeping humidity below levels that support storage fungi. Substantial storage losses can be caused by fungi that flourish in moist grain and by insects that can reproduce rapidly in warm grain. These losses result from interactions between the components of the stored-grain ecosystem, affected by the grain and ambient weather conditions. The role of aeration in this ecosystem is to uniformly condition the stored grain to a desirable low temperature and maintain desirable temperature and humidity conditions in the grain bulk by moving sufficient air of suitable quality through the grain. Aeration helps to equalize temperature throughout the grain bulk to prevent moisture migration and water condensation. The objective is to maintain the existing quality of bulk grain in storage. The purpose of this chapter is to guide grain managers on the concept of using aeration to preserve grain quality and manage insect populations in conventional farm and commercial grain storages.