Tanzania: Farmers dry maize carefully to reduce post-harvest losses

| October 14, 2019

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Tanzanian farmer Franael Martine harvests his maize after it matures and turns brown. Then he takes the cobs home for further drying, placing them on a tarpaulin for two or three days. To check if his grain is ready for storage, Mr. Martine bites a few grains with his teeth. If they are hard to bite, they’re ready. Some farmers can’t afford tarpaulins and dry their maize on the ground, on cement floors, on the roofs of houses, or in sisal sacks. Experts say this contributes to increasing moisture in maize grains, which favours fungal growth, including the fungi that produce aflatoxins. Well-dried maize also fetches better prices on the market.

It’s late afternoon and the weather is a bit cold. Franael Martine is wearing a white sweater to protect himself from the cold while walking through his maize field to check his crop. Although his maize plants look fresh and green, Mr. Martine says the cobs are maturing well, and will soon turn brown. He is optimistic that he will shortly start harvesting and drying his maize to avoid post-harvest losses.

He explains, “I have been growing maize for more than 30 years now. Drying maize is very important because well-dried grain lasts longer.”

Mr. Martine lives in Usa-River village in the Arusha region of Tanzania. In his area, farmers use three methods to dry maize before storage.

He explains: “You can leave maize to dry completely in the field before harvesting, or you can cut off maize stems with their cobs and put them in a pile to dry before harvesting, or you can harvest maize leaving stems in the field and dry the cobs at home.”

Of these methods, Mr. Martine prefers the third—taking the cobs home to dry them further. He says, “At home, I thresh and dry it on a tarpaulin (a large sheet of waterproof canvas) for two or three days.”

He says that piling stems with cobs in the farm is risky because birds, ants, and other pests often destroy the maize grains. He adds that drying maize on a tarpaulin for a few days after harvesting ensures that the grain has dried sufficiently to be stored.

To check if the grain is ready for storage, Mr. Martine usually bites a few grains with his teeth. If they are hard to bite, they are ready to be stored.

Dinna Alex is a maize farmer from Usa-River village who has been growing maize for more than 15 years. When her maize plants turn brown, she, like Mr. Martine, harvests the cobs and takes them home for further drying.

Mrs. Alex says that, during the drying period from July to September, her area experiences mists that disturb the drying process. Mrs. Alex dries her maize on a tarpaulin and, when there are mists, folds it over the grains to protect them.

Like Mr. Martine, Mrs. Alex also bites maize grains to check if they are dry enough. Then she winnows the maize before storage to remove waste materials such as pieces of husk or stalk.

Fatuma Chelangwa works at the Tanzania Agricultural Research Institute. She says the research organization recommends tarpaulins to farmers because they are cheap and easy to find. A five square-metre tarpaulin sells for 25,000 to 30,000 Tanzania shillings ($11 to $13 US), and one tarpaulin can be used to dry 200 kilograms of maize.

To check if the maize is dry enough for storage, Mrs. Chelangwa says that farmers can either use a moisture meter to measure moisture content, bite the grains, or use the salt and bottle method.

She says that many farmers prefer using the bite method because it is easy and cheap.

For those that want to use a moisture meter, it’s recommended that farmers dry their maize to 13% moisture content. However, many farmers find the method expensive and the meters are not commonly found in the market.

To use the salt and bottle method, Mrs. Chelangwa says a farmer needs to put salt in a dry and transparent bottle, add maize, close the lid, and let it sit for 12 hours or more. If the salt sticks to the sides of the bottle after shaking it, the maize is not dry enough for storage.

She says there are several benefits to drying maize carefully, including keeping the maize grains safe from pests and fungus, avoiding decay, and maintaining quality.

Because some farmers cannot afford tarpaulins, they use unsafe methods of drying. According to Mrs. Chelangwa, these include drying on the ground, on cemented floors, on the roofs of houses, or in sisal sacks. She says these methods are unsafe because they contribute to increasing moisture in maize grains. Moist conditions favour fungal growth, including the fungi that produce aflatoxins.

Mr. Martine says that well-dried maize fetches good prices on the market because buyers prefer it—and this has helped him improve his income. He adds, “I use the money from maize to pay school fees for my children, prepare a good diet for my family, as well as to pay bills like electricity and water.”

This resource was produced with support from The Rockefeller Foundation through its YieldWise initiative.