'Push-pull' agriculture stems migration into cities

By Keya Acharya

More than 25,000 small farmers in East Africa have multiplied yields with push-pull cultivation, in which Desmodium planted alongside maize pushes out pests while Napier grass planted along the borders pulls them in. The method could be used in India to good effect

Dr. Zeyaur Khan at ICIPE
Dr. Zeyaur Khan at ICIPE

From afar it’s a typical scene from Africa: a scientist standing amidst a field of maize. But neither Dr Zeyaur Khan nor the maize plot behind him are typical of anything African, or even global. Both are unique as innovative answers to food security in Africa. And perhaps for millions of small farmers in India and the developing world.

Dr Khan is a pioneer of the ‘push-pull’ method of agriculture, something that sounds complicated but is in fact a simple method by which small farmers on individual plots of land can increase their yields significantly, contributing to the food security of the country.

The East African (Kenya, Uganda, Tanzania) staple maize is plagued by a stem-borer cereal-eating pest and by the parasitic Striga weed that strangles the plant. These countries lose US$7 billion alone due to the Striga weed, and $5-6 billion to the stem–borer, says ICIPE, the International Centre for Insect Physiology and Ecology, based in Mbita on the shores of Lake Victoria in Kenya.

In sub-Saharan Africa, 6,122,000 ha out of the total maize area of 25,375,000 ha are stricken with Striga.

‘Push-pull’ was devised on experimental plots at ICIPE. Scientists took around 15 years to prove conclusively that the system works and works well.

The method involves interspersing the maize planted in a plot with the Desmodium plant species. This plant repels the stem-borer; it is in effect ‘pushed out’. Also, it is attracted to the Napier grass that is planted as a border on all four sides of the plot; this acts as a ‘pulling’ agent for the pest. And so the system is called ‘push-pull’.

“I discovered that Desmodium kills the Striga weed quite by accident,” says Khan. Experiments later proved him right.

In the ICIPE fields, the visible difference in a ‘push-pull’ plot and a ‘normal’ one is remarkable. The method yields 3.5 tonnes of maize per hectare, whereas previously the same hectare yielded less than 1 tonne of maize. Ninety-nine per cent of Africa’s farmers are smallholders who do not use either chemical pesticides or fertiliser on their lands.

Agnes Mbuvi surrounded by Napier grass in herharvested maize plot

Khan is critical of organisations like the Gates Foundation which promotes the use of external seeds and fertiliser in Africa. The Alliance for a Green Revolution in Africa (AGRA) also faces criticism -- even from the media in East Africa -- for its stance of “sitting on the fence” on genetically modified crops, as senior Zambian journalist Newton Sibanda called it.

Zeyaur Khan and ICIPE have proved that indigenous systems of agriculture work best. The Desmodium plant retains moisture in the soil while its roots produce as much as 110 kg of nitrogen per hectare per year. Both Desmodium and Napier grass are excellent fodder plants that have been proved to raise milk yields in household cows; the expensive Desmodium seeds also give the farmer a good income.

The ‘push-pull’ method thus takes care of moisture retention, soil fertility, serves as a pesticide, and integrates livestock and livelihoods into the system by providing fodder and income from seeds.

“We don’t need much money, we need appropriate technology,” says Khan. “Two dollars is the magic number for Africa. If a farmer can earn more than $2 a day on his farm, which is the amount he would earn if he migrated to the city, he will stay on his farm. This method ensures him that amount.”

At Ebukanga village, some 40 km from ICIPE, 45-year-old Agnes Mbuvi  tells us her half-acre ‘push-pull’ plot has given her six bags (one bag equals  90 kg) of maize since 2002, when she first adopted the method. She says she requires seven wheelbarrows of manure now against the previous “many more” wheelbarrows and fertiliser. She also does not have to hear complaints from her neighbours about encroaching cattle.

“I have enough maziwa (milk) throughout the year, enough food year-long, and the soil is easy. I am happy,” she says.

Agnes adds that the income she earns from the extra maize, milk and seeds has helped her raise and educate her children.

So far, 25,000-30,000 farmers in East Africa have adopted the ‘push-pull’ system, most of them in Kenya. The percentage, however, is still low -- just 15% of farmers in Kenya -- pointing to the need for wider dissemination of the method.

“A school education helps change mindsets,” says 50-year-old Elfas Ameyo, a part-time plumber and part of a wider majority of rural Kenyan farmers who are literate. Numerous Christian missions in rural areas have also helped spread the use of English among schooled farmers. Ameyo’s unschooled neighbour has watched Ameyo’s plot and its 10-fold yield for some years. But he is still hesitant to follow suit.

Ameyo has a one-fourth-acre ‘push-pull’ plot that has been giving him 180 kg of maize since 2002; earlier, he used to get 16 kg from the same plot. The maize provides him and his family food for six months.

The good news for India is that ‘push-pull’ has so far been successful in rice plots too. ICIPE is now trying the method on cotton to repel the cotton bollworm, and has completed three seasons on its experimental plots. The roots of the cotton plant also produce chemical flavinoids and isoflavinoids that kill the Striga weed.

“This method stems migration,” says Khan. “You can have two crops, one food crop and cotton as the cash crop.”

“I don’t see any limitation on using the ‘push-pull’ method in the Indian situation,” says Dr Christian Borgemeister, director of ICIPE. “We are happy to share any information we have with Indian research institutions.” 

Although India has indigenous systems of knowledge that involve using insect-repellent plants, a tried-and-true modern-day scientific method still has to be formulated and taken up on a large scale by the government. Eminent agricultural scientist Dr M S Swaminathan agrees that the ‘push-pull’ method will ensure both soil health and crop security. He says: “Such a method can be adapted to different growing conditions by the appropriate choice of crops.”   

(Keya Acharya is an investigative reporter who writes on women, environment and other development issues)

Infochange News & Features, May 2010