Wiring for fans and electrical components needs to be checked for corrosion and broken insulation. Any exposed wiring should be routed through dust-tight, waterproof conduit. Fans in particular should be cleaned thoroughly to remove dust and dirt, so as to improve operating efficiency. Bins should also be thoroughly cleaned with brooms and vacuum cleaners. If at all possible, new grain should not be put on top of old grain because of the potential for mold and insect contamination of the new grain.
Initial grain condition
Clean, sound grain is easier to store than cracked, broken grain. Broken kernels mold three to four times faster than whole kernels. In addition, broken grain is more susceptible to insect attack. The least grain damage generally occurs at moisture contents of 18% to 20%.
Fines and broken kernels also disrupt airflow distribution which contributes to storage problems. Thus, your farmer customers have hopefully cleaned their grain before delivery to your elevator. If not, and you receive low-grade grain, it may be worth using a grain cleaner to remove fines before placing the grain in storage. Cleaning is easier and more complete at low flow rates, and with dry grain.
After filling a bin or silo, the grain surface should be made level with a grain spreader as peaks increase airflow resistance. In addition, a spreader will more evenly distribute fines throughout the grain mass, resulting in more uniform airflow.
Trade-offs occur here — as utilizing a grain spreader tends to pack the grain tighter, allowing for more grain to be stored, but increases airflow resistance, which can contribute to hot spots in the grain mass. A stirring device can be used to loosen the grain — but again, additional trade-offs occur: Excess use can contribute to grain damage.
Grain moisture is one of the key determinants of grain quality. If moisture is too high, even the best aeration equipment and monitoring will not keep the grain from spoiling. Recommended moisture contents for stored grain are listed in the table below. These recommendations refer to the wettest grain in the bin, not the average moisture content.
If high temperature drying is utilized, your dryer should be operated at the lowest temperature possible. High temperatures reduce grain quality and make kernels more susceptible to breakage and stress crack development. Excess temperature also binds lysine in corn, making it unavailable to livestock. High temperature drying should be stopped when grain moisture reaches about two percentage points above your desired final moisture content. The remaining moisture will be removed in the cooling process.
Cooling to ambient temperatures should take place over a four- to six-hour period. During this time, the grain “steeps,” where kernel moisture is redistributed and equalized. Cooling grain too rapidly can cause stress cracks; cooling too slowly encourages spoilage.
Putting your grain into storage at the proper moisture doesn’t guarantee that it will stay that way. Moisture can be reintroduced through leaks in your bins, hatches left open or via other ways. Condensation can also cause increased moisture content; it is common — particularly on roofs and sidewalls — when warm grain (50 F or above) is cooled during cold weather (30 F or below), or when hot grain from a dryer is cooled in a storage bin.
Condensation can be reduced by cooling stored grain in stages during the fall; cooling hot grain from the dryer in a separate cooling bin before storage; and by providing adequate exhaust vents in the cooling bin.
Aeration, the movement of low volumes of air through your stored grain, is necessary to keep the grain cool and to slow mold growth since both wet grain and molds respire and give off heat. Aeration is needed to keep grain at the desired temperature and to keep temperatures equalized — even if grain is dry and cool when placed into storage.
Airflow rates typically range from 0.1 to 0.75 cfm/bushel. Well aerated grain can generally be stored safely about four times longer than nonaerated grain.
Temperature differences within binned grain can create convection currents that move and concentrate moisture in the top center of the bin. Moisture movement problems can be minimized by keeping grain mass temperatures equalized and within 10 F of the average monthly outside air temperature.