How Kiambu farmer utilises Mexican Marigold weed as home-made fertilizer

By George Munene

Mex­ican Marigold (tithonia di­ver­si­fo­lia) is for many farm­ers no more than a men­acing weed. For Allan Kamau, a mixed farmer in Ki­ambu County, however, using the read­ily avail­able weed known for its char­ac­ter­istic yel­low/or­ange flowers and strong odor has en­abled him to es­chew ex­pens­ive store-bought fertilizers.​as well as in­creas­ing his ar­row­root yield.

“Ini­tially, I was using a fo­liar fer­til­izer made from water hy­acinth, but with a kilo­gram cost­ing Sh240, I found the price too ex­or­bit­ant while I did not ob­serve a marked im­prove­ment in yield. I em­barked on find­ing more cost-ef­fi­cient or­ganic fer­til­izer op­tions,” Allan ex­plained. 

A Bio­lo­gical sci­ences gradu­ate, Allan stumbled on the idea of using tithonia as an or­ganic fer­til­izer while an in­tern at Kalro, Kandara. “After read­ing that it con­tains a high amount of NPK; Ni­tro­gen, Phos­phorus and Po­tassium and the pos­it­ive im­pacts it had had for potato farm­ers who cut and bur­ied it into trenches, I de­cided to in­cor­por­ate it in grow­ing my own tuber crops,” he said.

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On his 30×5-meter plot of ar­row­roots, the young farmer has ap­plied Mex­ican Marigold ex­trac­ted fo­liar for two sea­sons now. Not only him­self but his neigh­bors as well at­test to an im­prove­ment in his crop; “Hizindomazakoun­azi­fa­nyianini?” is a com­mon re­frain he gets from neigh­bor­ing farm­ers.    

Col­lo­qui­ally re­ferred to as maroro, Allan soaks tithonia leaves plucked from a fence on his fam­ily home in a con­tainer and al­lows them to rot for three weeks. He for­ti­fies this with ash, crushed egg­shells and bio­gas slurry which en­riches the mix­ture and of­fers a more com­plete meal for his crops. Be­fore ap­plic­a­tion, he sieves the mix­ture be­fore adding equal parts of water. 

Ash con­tains sig­ni­fic­ant amounts of po­tassium and cal­cium while provid­ing smal­ler amounts of phos­phorus and mag­nesium and mi­cro-nu­tri­ents like zinc and cop­per. Egg­shells are prob­ably the best nat­ural source of cal­cium con­sist­ing of up to 93 per cent of cal­cium car­bon­ate as well as trace amounts of min­er­als and other ele­ments which make it an ideal or­ganic fer­til­izer. Cal­cium also acts as an or­ganic pesti­cide that de­ters cer­tain pests without the need for chem­ic­als.

He feeds the fer­til­izer dir­ectly onto the tuber stems every week after plant­ing be­fore the plant’s leaves de­velop their char­ac­ter­istic can­opy. “The leaves are often a prom­in­ent green with ro­bust stems,” he elatedly ob­serves. Tuber size is dir­ectly tied to the size of the feeder stem, con­sequently, the big­ger the stem is the more kilo­grams one har­vest.

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Hav­ing run suc­cess­ful tri­als on ar­row­roots, he is plan­ning on ob­serving the per­form­ance of a vari­ety of crops such as cof­fee under its ap­plic­a­tion. 

Per in­fonet bio­vi­sion, when in­ter­planted with other crops tithonia has been ob­served to im­prove yields. This in­cludes ve­get­ables like kale, French beans and to­ma­toes as well as fod­der crops such as Napier grass.

Tithonia also acts as a soil im­prover. Maize is known to re­spond well when its leaves and cut­tings are ap­plied. The best res­ults are ob­tained with the ap­plic­a­tion of 5 t/ha of leafy dry mat­ter.