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Keep in control maize losses this rainy season

Saturday November 11 2017

Dr Jane Ambuko, a senior lecturer at the University of Nairobi’s Department of Plant Science and Crop Protection.

Dr Jane Ambuko, a senior lecturer at the University of Nairobi’s Department of Plant Science and Crop Protection, and a Principal Investigator of YieldWise Postharvest Project, which is funded by the Rockefeller Foundation. PHOTO | COURTESY 

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As maize farmers harvest their produce, a good chunk of the grain could be lost, especially due to the ongoing rains.

Brian Okinda spoke to Dr Jane Ambuko, a senior lecturer at the University of Nairobi’s Department of Plant Science and Crop Protection, and a Principal Investigator of UoN’s YieldWise Postharvest Project, which is funded by the Rockefeller Foundation, on measures farmers and the government can take to safeguard the staple crop.

What is the level of postharvest loss in the maize supply chain?
There are two kinds of losses that occur in maize namely quantitative (lost kilos/volume) and qualitative. Quantitative losses are easy to determine and report since they constitute a physical reduction in the marketable volume and can be easily measured.

In Kenya, the figure may range from 10–20 per cent of the total volumes. Qualitative are due to loss of aspects such as nutritional, safety or grade and are hardly considered a loss or reported as such.

What factors contribute to the losses in maize?

The two losses begin from the field and continue through the other postharvest handling stages. Some farmers cut their maize and leave it in the field for too long, exposing the crop to fungal rots leading to qualitative losses.


Poor traditional processing practices like where sticks are used to ‘beat’ grains off the cobs results in lots of broken grains (qualitative loss) and also predisposes the grain to other deteriorative agents including aflatoxins.

Poor grain drying also predisposes it to aflatoxins. There are other loss agents such as spillage.

During storage, the key agents of postharvest losses are pests, mainly weevils which can lead to 100 per cent loss. Rats also contribute to high storage losses.

Contamination from aflatoxin is a major contributor of qualitative losses during storage. Aflatoxin contamination is predisposed by other factors such as poor drying, damaged (broken) grain and dump or not well-aerated storage.

What measures should farmers take to reduce postharvest losses in maize?
Farmers should not delay harvesting their maize once it is mature; prolonged stooking in the field exposes the grain to rot. Farmers should also be assisted to access simple processing technologies such as shellers instead of the common traditional methods used.

After shelling, the maize must be dried properly to the recommended moisture content level of about 13 per cent before storage. There is a special tarpaulin that farmers should use to dry maize and other grains. Using the tarpaulin makes the grains dry faster.

After drying, the maize should be stored properly in a clean, dry and well-aerated store to avoid contamination and infestation by pests.

One of the storage technologies recently introduced in the Kenyan market are hermetic bags. The principle behind hermetic storage (bags or silos) is keeping oxygen out of the bag or storage container. This suffocates the storage pests such as weevils which cannot survive without oxygen.

The hermetic bags/silos are readily available from various agro-dealers. The 90kg storage bag retails from Sh200 to Sh250 and can be reused several times.

How dangerous are aflatoxins and how can farmers reduce their level in maize?

Aflatoxins are a slow killer. Chronic dietary exposure to low doses of aflatoxins is a known risk factor for liver cancer and other health-related issues.

Unfortunately, most of us are unknowingly consuming food with unacceptable levels of aflatoxins. Aflatoxin contamination of maize can occur at any stage, from production, harvesting, postharvest handling, processing, storage and distribution

To reduce aflatoxin infection, harvest at the right stage of maturity; dry well; handle grain properly to avoid contact with soil or damage that predisposes them to fungal contamination, sort out damaged grain, use proper storage facilities and control pests.

There is a relatively new innovation called ‘Aflasafe’ from the International Institute of Tropical Agriculture (IITA). IITA is working with Kalro to promote Aflasafe in Kenya. Besides Aflasafe, there are many other technologies and innovations being promoted to address aflatoxin infestation.

YieldWise is one of the initiatives aimed at helping farmers curb postharvest losses. What does it involve?

YieldWise project is supported by the Rockefeller Foundation and works in four value chains to reduce half the current postharvest losses by the year 2025. This is the target set under the Malabo declaration (2014) of the African Union Commission.

YieldWise focuses on four value chains including mango (Kenya), maize (Tanzania) and tomato and cassava (Nigeria).

In Kenya, teams from the University of Nairobi, JKUAT and Technoserve are working to reduce post-harvest losses.

Although the focus in Kenya is not maize, the lessons the partners working on the maize value chain in Tanzania are always shared quarterly.

With a looming maize shortage due to low rainfall (early in the season) and worsened by fall armyworm attack, what can be done to cushion consumers from any adverse effects of the situation?

Smallholder farmers are facing a very difficult situation and it’s great that the government is offering to buy all the maize from them. The only challenge is that it is a wet harvesting season. The wetness predisposes the maize to high postharvest losses especially from aflatoxin contamination.

Therefore, even the little yields realised will still be lost because of unfavourable conditions for drying and lack of adequate and proper storage facilities. Farmers should be assisted to dry and store their grains during this wet weather. Otherwise they will lose a huge proportion of their produce.