Keep in con­trol maize losses this rainy sea­son


Daily Nation (Kenya) - - SEEDS OF GOLD -


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

Okinda spoke to se­nior lec­turer at the Uni­ver­sity of Nairobi’s Depart­ment of Plant Sci­ence and Crop Pro­tec­tion, and the 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.

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