A large percentage of the world’s population consumes grains, which include cereals and pulses. However, even when all the factors of production remain constant, poor handling can compromise their quality and quantity, and lead to massive post-harvest losses.Loss of quality leads to reduction in the amount available for sale, while poor quality results in reduced market opportunities and nutritional value.Proper post-harvest handling, conservation and storage enable grain quantity and quality to be maintained.
Tips to protect your grains from contamination and spoilage:
Harvest in good time
It is critical to harvest maize once it shows signs of maturity. Maize left in the field for long is prone to pest attacks and rotting, especially in wet conditions. The moisture absorbed during this extended time will contribute to spoilage and growth of fungi and mycotoxins harmful to the body.
Dry your maize
Once maize is harvested, it should be dried before storage. The sun’s heat rids maize of moisture and kills pests and their eggs. Stir your grains so that they dry evenly. Maize should have a moisture content of 13.5 per cent before storage. Use a moisture metre to check the moisture level. If not available, farmers can use an empty soda bottle and salt, as explained below:
How to test for content moisture:
- Put a handful of dried maize in a dry soda bottle and add ½ handful of salt.
- Shake the bottle for 2 to 3 minutes. Allow the grains to settle at the bottom of the bottle. If the salt sticks onto the sides of the bottle, the maize is not dry enough for storage.
- Dry the maize again and repeat the test until no salt sticks on sides of the bottle. The maize can now be stored and there is no danger of it developing mould (or aflatoxins).
Storage
- The store
For sustained dryness of the grains, ensure your store has 40-50 per cent free space. Place grains on a raised platform 60-90cm above the ground, to allow for air circulation. Before storing the next season’s yields, clean the store to get rid of pests and their eggs from the previous stock. Some pests hide in wood cracks, while others remain in the bags for long periods. To get rid of such pests, soak the bags in hot water.
- Storage techniques
How to conserve grains organically:
- Use of plant extracts and/or parts
Extracts from plants such as neem and pyrethrum play a major role in grain storage and preservation. Chilies, too, can be used.
Procedure:
- Get the plant extracts and/or foliar and dry in the sun. Grind and crush the plant to a fine powder or small particles.
- Put your well-dried grain in bags, add the plant extracts and mix well by shaking them.
- Seal the bags and place on wooden surfaces away from sunshine and rain and water.
- Use of diatomaceous earth (diatomite)
Diatomite is a natural white mineral that helps in the conservation of grains. It is ground into a powder called diatomaceous earth for use as a grain preservative:
- Ensure that your grains are well-dried;
- Get high quality bags;
- Apply the diatomaceous earth at the bottom of the container or bag. Put a layer of 3-4 inches of grain on top of the mineral. Add a second layer of the element, and another layer of 3-4 inches of grain until the bag is full;
- Tightly close the bag and shake thoroughly. If the bag is heavy, roll it for a few minutes to ensure the diatomaceous earth mixes well with the grains;
- Open the bag and add the final layer of the mineral. Close it to ensure that it is air-tight and store on top of a wooden surface, away from rainfall and sunshine;
- Diatomite absorbs extra moisture from the grains and prevents buildup of mold;
- Ensure that you use food grade diatomaceous earth.
- Metallic silos
Use of affordable and portable metallic and plastic silos for storing grains can reduce post-harvest losses by 30 to 50 per cent. You can obtain them from the Kenya Agricultural and Livestock Research Organisation (Kalro) and private companies such as Kentainers.
For proper use of silos, the following procedures should be followed:
- Buy your plastic or metallic silo from a reputable organisation. Place it on a wooden surface to prevent corrosion, and protect it from rainfall and excess sunshine;
- Clean your grains and dry them to a moisture content of eight to 10 per cent before loading into the silo;
- Fill the silo but leave a small space close to the opening;
- Put a candle into the silo and light it, then close it with the candle inside;
- The candle will burn for three to four minutes and use the little available oxygen, after which it will go off. Any insects such as weevils in the grains will die due to suffocation;
- One metallic silo can store up to 1,000kg to 1,500kg of grains.
With good post-harvest handling and storage techniques, we can save a lot of grains and boost food security.
PICS bags
The Purdue Improved Crop Storage bag (PICS) is efficient in protecting grains, as it is multi-layered with plastic material that deprives pests of oxygen and prevents air circulation in the stored grain leading to their death. They are better than the ordinary woven sacks, which allow weevils and other destructive pests into the grain. The outer part of the PICS bag is made of woven material for easier handling. You can store your grains in a PICS bag for many months and the quality will remain uncompromised. They are sold at Ksh200 at most agrovets.
However, if not available in your area, you can purchase them through Bell Industries Ltd, phone no: 0733 764 562.