premature harvesting fanning the aflatoxin menace

Premature harvesting and poor storage techniques of grains are the main causes of the aflatoxin poisoning in maize that plagues regions of Eastern and Coast provinces, reports a local agricultural NGO Alliance for Green Revolution (AGRA).

AGRA has now teamed up with local cereals boards in an initiative dubbed ‘storage and post harvest management.’ The initiative educates farmers on handling grains before and after harvesting and advises on the right conditions to store them.

This initiative that commenced last year has seen AGRA working with roughly 38,000 farmers in Rift Valley and around 3000 farmers in Eastern Province. “We are building their skills to take care of the situation,” said Anne Mbaabu, AGRA’s Market Director.

The AGRA initiative will also sensitize farmers on gauging the right moisture content before harvesting their grains. “At harvest the grain’s moisture content shouldn’t exceed 13.5 percent,” said Anne. 

However, most farmers unknowingly harvest early when the moisture content is over the 13.5 percent mark or end up storing maize in damp environments. That causes the mycotoxins fungi to grow on the grains. Some of these mycotoxins have toxic varieties that kick-start the growth of fungus that generates the aflatoxins.

The weather also plays a role in exacerbating the aflatoxin menace as it happened this year. In May, the aflatoxin contamination as per Anne was caused by rains that came early before farmers were done harvesting. “It was due to climate change,” she said. The maize got damp, triggering the growth of the mycotoxin fungus.

The general arid weather of Eastern and Coast Provinces makes the two regions more prone to aflatoxin contamination than Rift Valley. A report this year, on the two provinces by the Public Health Ministry showed that 70 percent of maize produced by both regions had aflatoxin contamination.

The arid weather of the regions causes what Anne refers to as the moisture stress factor. That happens when growing maize in the field lacks sufficient moisture causing mycotoxins fungi to be generated.

Some of these toxic fungi are visible or invisible on the grains’ surface. But even when the visible fungi on grains are cleaned; it doesn’t make the grains any safer to consume by either humans or animals.

To pre-empt errors of early harvesting of grains by farmers, there exists a moisture meter that measures the grains moisture. That however is not affordable to many small holder farmers as its costs range from Sh30, 000 to Sh70, 000.

But according to Anne, there are simple techniques such farmers can use to assess if their maize is at right moisture content at harvest time.

The techniques include shaking maize in a tin and listening to hear if a crackling sound is produced or placing a grain on ones teeth to test its resilience. “If the tooth easily grinds the grain,” said Anne, the maize is not ready to harvest.  “Seasoned farmers know these methods,” she said.

Anne also advises against drying the maize on the ground and advocates for drying on a surface like trampoline so that in case of rain, the maize can be covered. But once the drying maize is in a secure shelter “it should be left open,” she said as covered maize generates moisture that triggers the fungi growth.

Another low cost technique Rift Valley farmers are using is cutting their maize stalks and stacking them in pyramid shaped heaps and leaving them to dry in heaps for up to two weeks before taking it home. The stack ensures even when it rains water drains down the stack without it getting to the grains.

Aflatoxin is known to cause liver cancer also incidences of Hepatitis B have been reported where grains affected by aflatoxins were consumed. Death from aflatoxin infection can occur within 48 hours.

Aflatoxins can’t be destroyed by cooking “its heat stable,” said Anne. Even milk consumed from cows fed on grains contaminated by aflatoxins is risky to consume. Such grains are also dangerous for animal consumption.

That has made some researchers deem the only safe use for such grains would be for generating ethanol energy.  Other than that “the grains should be burnt,” Anne said.

AGRA’s post harvest management initiative has provided farmers pooled into groups the moisture metres in Eastern province regions like Meru, Embu and Northern and Southern Rift Valley regions of Transmara.

Maize that’s properly dried and bulked by the farmers’ groups according to Anne gives them more bargaining power and they stand to fetch a higher price for their produce. As opposed to if they each sold the grain individually.

This year infections of less that 10 infections aflatoxin poisoning were reported though there were no casualties like in 2004 when almost 130 deaths were reported.

Written By James Karuga for African Laughter

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