Kenya : intercropping for weed control and soil fertility enhancement (African Agriculture)

Read at : African Agriculture

Kenya project uses intercropping for weed control, soil fertility enhancement

So close physically, yet so far apart in output; is an accurate description of maize fields in a section of western Kenya. Despite having the same ecological characteristics and being only a metre apart, the same-sized plots yield varying amounts of maize—sometimes with a difference of more than six bags. The yield difference is influenced by soil quality and a weed called Striga has depleted the once fertile plots. The farmers have tried everything to control the weed – which affects maize, sorghum and millet, among other crops – and many of them have lost hope of ever getting rid of the deadly plant. But the few who have embraced the Tropical Soil Biology and Fertility programme (TSBF) have a reason to smile, as their harvests have doubled in the past two years. TSBF is a programme that encourages farmers to intercrop legumes with cereals in order to replenish their soil; use phosphates, manure and also apply other interventions aimed at weed control. The new breed is coated with herbicide that kills germinating Striga as it attempts to invade the maize and has the capability of controlling the weed in two years time. According to the farmers who adopted the maize variety, the future is now bright. However, they maintain that they have to use fertilisers that enrich the soil and also practice inter-cropping so as to reap the benefits.
The extension officers have recommended soy beans to the farmers because the crop has a high nitrogen fixation rate, and its nodules produce a toxic liquid that creates unfavourable conditions for the striga weeds.

Mr Makokha says that he now harvests up to six bags of maize from the same one-acre plot that used to produce less than one bag. Next to his farm is another plot with stunted malnourished plants. The owner, Mrs Margaret Atieno, says she never bothered to apply the new methods recommended by TSBF. On her one acre plot, she has never harvested a full sack of maize and says that she finds it hard to adopt the inter-cropping system since she has a small piece of land and cannot afford to buy the recommended fertilizer.

In an effort to find a lasting solution to the Striga infestation, they have now come-up with a legume known as Mukuna puriens, which TSBF officers say is capable of controlling the Striga weed permanently.

TSBF extension officers say that farmers have not adopted the legume because it is poisonous to both plants and animals, and no by products can be manufactured from it. “The legume is planted and the land abandoned for two years. Animals cannot eat it since it is poisonous hence most farmers shy away from planting it since they have small plots and view the strategy as wastage of land,” says Mr John Mkalama, a research assistant with TSBF.

But he recommends the legume in cases where the farmers have totally abandoned the fields, which have now turned into flower farms. “We encourage farmers who have abandoned their plots to instead plant the legume and come out of the situation in two year’s time” says Mr Mkalama.

He says: “One can mistake the fields for flower farms due to the nature of the weed growth and there is alarm that if the wild plant is not controlled, the region which has been perceived to have good soils and high yields might soon be different.”

To avert the situation, Alliance for a Green Revolution in Africa (AGRA) has announced plans to launch a new intervention early next year, which would help the farmers improve the soils and restore the nutrients.

At the same time, Mr Mkalama says the Kenya Plant Health Inspectorate Service (KEFIS) has researched on the effectiveness of the soy beans in enriching the soil and would release six potential varieties early next year to the farmers. He said the farmers were exploring 61 varieties that TSBF imported from West Africa, Zimbabwe, Tanzania, International Agricultural Training Abroad (IATA), and Uganda.

He added that the soy bean, which was introduced in the region in 1986 by Mumias Sugar Company, has been recommended since it is capable of fixing nitrogen deep into the soil. Striga produces seeds that remain viable in the soils for 20 years, until they are stimulated to germinate by biochemical signals from host plant roots.


Business Day Africa

Author: Willem Van Cotthem

Honorary Professor of Botany, University of Ghent (Belgium). Scientific Consultant for Desertification and Sustainable Development.

Leave a Reply

Please log in using one of these methods to post your comment: Logo

You are commenting using your account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: