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Where the savvy go for organic farming lessons

Friday October 20 2017

An employee at Grow Biointensive Agriculture Centre of Kenya (GBIACK) in Thika examines vermicompost.

An employee at Grow Biointensive Agriculture Centre of Kenya (GBIACK) in Thika examines vermicompost. All the crops at the centre, from vegetables to fruits and onions are grown using vermicompost or simply worm manure. PHOTO | WILLIAM INGANGA | NATION MEDIA GROUP 

William Inganga
By William Inganga
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The Grow Biointensive Agriculture Centre of Kenya (GBIACK) based in Thika is an interesting place to be for any discerning farmer.

Here, you find crops and other plants being grown in soda bottles, dug out banana stalks and ooh, worms are at the centre of it all.

All the crops, from vegetables to fruits and onions are grown using vermicompost, or simply worm manure.

“Chemical pesticides and fertilisers have no place here because they kill worms, insects and other organisms that play a pivotal role in the decomposition of garden and kitchen refuse,” say Samuel and Peris Ndiritu, the couple behind the centre.

Ndiritu, who holds a BA in Community Development from the University of South Africa, says the idea is to encourage people to grow their crops organically on their kitchen gardens and farm intensively on small parcels.

“Families generate a lot of kitchen waste, which can be turned into good manure with the help of worms.”


To make manure, he says one begins by raising the worms even in a bucket or a shallow pit of about one-and-a-half feet.

“Worms are spread on dry, shredded bedding and tap or rain water is sprinkled over it. The waste is spread out and covered with an inch of more bedding to make the surface dark. The bedding is watered regularly to keep it moist.”

Kitchen refuse, which include food leftovers, peels from potatoes, fruits and vegetables are shredded or pounded and are placed in the decomposing pile underneath the surface bedding.

The worms would feed on the waste, which should be kept wet.

After three-four months, the trash would be ready to be transferred to a raised structure whose sides are made of timber and a perforated base to allow aeration and drainage.

A roof is recommended for the structure to cut out direct sunlight that might scorch the worms. One ends up with vermicompost from the red worms (Eisenia foetida).

At the two-acre GBIACK, which cost the couple Sh1.2 million to set up in 2009, every space matters as it is evident that no matter how small a farm is, the basic nutritional needs of a family can easily be met.


The centre grows onions, lettuce, sukuma wiki (collard greens), garlic and spinach in sack gardens.

Other crops are grown in recycled soda bottles and dug out banana stalks.

“Instead of burning or throwing them away, we recycle and grow vegetables in them. It’s very easy so long as the soil is fertile and the crops are shallow-rooted,” says Samuel.

Banana trunks too serve as good hosts for shallow-rooted crops. After cutting a banana plant, the inner layer of the trunk is removed, retaining the outer part.

Soil with adequate compost is then filled in the trunk and crops planted.

“Banana stems hold water for long,” says Peris, “You can grow crops in the stem for up to six months. After this time it rots and we use it to make compost.”

Peris Ndiritu, who is a co-proprietor of the
Peris Ndiritu, who is a co-proprietor of the centre (right) and crops grown in a banana stalk at the centre. As land sizes are shrinking faster due to sub-divisions as real estate takes the rest, what we need to produce more food are intensive farming techniques. PHOTOS | WILLIAM INGANGA | NATION MEDIA GROUP

Apart from the worm compost, there is what Ndiritu calls cold compost.

Cold compost is made from waste of crops like amaranth, maize, wheat, sorghum and millet harvested from the farm.
It is heaped together with weeds and grass; anything that’s green in nature.

The stack is capped with a layer of topsoil, which introduces micro-organisms required for decomposition.

Sufficient decomposition occurs after six to eight months.

The result is the compost manure rich for use on the farm.

Crops on the dozens of beds at the centre are close-spaced in an unconventional way of farming. Peris indicates that this method is borrowed from nature.

“If you enter a natural forest, you won’t find trees growing in straight lines. Such a method allows a large population of crops to maximize on space,” she says.

She allays fears of plants competing for nutrients since enough compost would have been applied during bed preparation.


Where crops grow intensively, a mini-climate is formed underneath the leafage. Evaporation is, thus, minimised as direct sunlight does not reach the ground hence the soil remains wet.

On some patches, more than one crop is being grown. Arrowroots and black nightshade do well together. “The arrowroots act like an umbrella for the young seedlings,” explains Peris. “Once we harvest the arrowroots, we’ll remain with the black nightshade.”

The couple, who both hold Diplomas in Sustainable Agriculture from Mannerhouse Agricultural Centre in Kitale, say that in bio-intensive farming, the farm is not allowed to rest. So long as adequate compost is generated, productivity could be sustained.

Besides having a propagation house where seedlings are raised, the couple also have a seed bank that preserves seeds raised from the farm for future use.

“Land sizes are shrinking faster due to sub division as real estate takes the rest. What we need to produce more food are intensive farming techniques,” says Ndiritu, adding they use some plants including onions as repellents to avoid the use of pesticides

Up to 40 farmers visit the centre for lessons every week, which consist of classroom sessions and practicals.

Dr Peter Okoth, a soil scientist, says mineral fertilisers are expensive thus organic farming saves cost.

“Earthworms are naturally present in the soil and during the rainy season, they can be dug out and one may begin rearing them.”

However, he notes organic farming at some stage becomes expensive because it requires more material than mineral fertilisers to reach the same level of fertilisation.

“Integrated soil fertility management which recommends a combination of biological and chemical fertilisation as the optimum way of managing soil fertility is the best way to go,” Dr Okoth asserts.