How to Store Grain and Seed More Safely

Traditional storage.  Typically, grain is stored in 40–50-kg sacks made of jute or woven plastic. The grain moisture content (MC) in these bags will fluctuate as moisture in the air can freely transfer through the bag.  A combination of high temperature and high relative humidity will lead to insect infestation in these bags even if the grain was properly dried before storage. Bags are usually stacked under a roof or in a shed and will likely need periodic fumigation to control insects. Some farmers use granaries made from timber or mud/cement, or large woven baskets that can also suffer from insect and rodent damage.

Sealed storage: For longer-term storage of grain and seed, sealed or hermetic storage is an alternative. In such storage, carbon dioxide builds up and oxygen decreases. The seed remains viable but insects cannot survive. Thus, ensuring complete sealing is important. If grain is dried to 14% MC and stored in sealed storage, this reduces the risk of insect and rodent damage and the grain should not absorb moisture from the atmosphere or be damaged by rain. For storage up to 1 year, grain needs to be dried to 13% MC or to 9% MC for storage longer than 1 year.  

Sealed storage containers come in all shapes and sizes. They could be a small plastic container, a sealed 200-liter drum, or more complex and costly sealed plastic commercial storage units. Most large commercial steel and concrete silos being used in Western countries can be sealed for fumigation.

Hermetic storage of grain has recently proved successful in keeping paddy seed viable for longer than 12 months. In the hermetically sealed storage environment, insects create an oxygen-deficient atmosphere that reduces insect infestation drastically to an acceptable level. Hermetic storage is a good option for storage of grain and seed where cold storage is not available or too expensive.

For storage of small seed lots, a variety of plastic bags or packages can be used. Different types of plastic have different resistance against transmission of water vapor. Glass jars, hard PVC, or bags containing aluminum liners will provide the best protection against moisture re-entry. Polypropylene or polyethylene bags are the next best choice. The use of paper bags or flexible PVC bags for long-term storage of seed is discouraged.

Importance of temperature: No bag or container can protect seed from the detrimental effects of high temperatures. For each 5 °C increase in temperature, seed storage life will decrease by half.