Safe grain post-harvest handling practices

One of the major stages in crop production is the collection of mature crops from the field, a process known as harvesting, and keeping the grain until the time it is needed for selling or domestic consumption, referred to as storage.

According to some estimates by the National Agricultural Research Organisation (Naro) Uganda currently loses over 17.6 percent of its maize due to poor post-harvest handling technologies which also creates molding by fungi in maize producing aflatoxins.

Taking too long to harvest maize from the field exposes it to rain and cold weather which may cause molding, shriveling, and discolouration of the maize grain as well as possible formation of aflatoxins.

Maize is a much traded crop in East Africa. Recently Uganda’s maize was rejected by the South Sudan government, reportedly because it did not meet the quality standards of that country. 

Aflatoxins are said to be cancer causing poisons detectable by aflatoxin testing strips. 

It is also dangerous to feed livestock on badly stored maize. Aflatoxins cause the same health problems to livestock as they do to humans.

Wherever maize is stored it is important not to place it directly on the ground to avoid mould and formation of aflatoxins. All harvested maize must be sorted and free of all foreign objects and damaged maize grains. 

The area all around the store should be well maintained and free of any form of rubbish to keep away rodents.

Placing dried maize in tightly covered plastic drums denies the pests oxygen and kills them without the need for chemical fumigants. 

Pics bags can also be used to store grain because once they are tightly closed by tying; the bags prevent entrance of oxygen, become hot, and form hostile conditions for the pests to survive.

A technology known as solarisation is used to kill pests that may have invaded grain. 

The technology endorsed by Naro uses heat to kill storage pests in grain. A pit of 3 ft wide and 30 cm deep is layered with 15cm of dry grass at the bottom to stop the grain from absorbing moisture. 

A black polythene sheet is laid on top of the grass on which weevil infested grain is placed. It is tightly covered with a transparent polythene sheet to block off air circulation. 

The weevils or pests are killed by high temperatures within two hours of sunshine.

Mr Michael J Ssali is a veteran journalist, 
[email protected]