By Joanna Wolstenholme
Organic farming seems to have earned itself a reputation amongst some in the scientific community for being unscientific and misguided. However, researchers at Rothamsted Research, in conjunction with the International Centre of Insect Physiology and Ecology (ICIPE), the Kenya Agricultural Research Institute (KARI) and the Kenya Ministry of Agriculturehave been doing their best to combat this image, and inject some innovation into the field.
In principle, there is not much to dislike about organic farming—a reduction in chemicals used to grow our foods can only really be a good thing; even if there is no link between eating organic and having better health (a recent study showed that those who ate non-organic foods were no more likely to contract cancer). For instance, a reduction in the energy required to produce and spray pesticides and herbicides would go a long way to making agriculture more sustainable. In poor subsistence farming communities, such chemicals are far too expensive to even dream of buying, so a cheap and effective alternative has the potential to radically improve yields.
Researchers at Rothamsted harnessed the power of compounds already produced by plants in their scheme for ‘Push-Pull’ companion planting, which has been implemented in West Africa, and produced great yield improvements. In this scheme, maize is protected from both the Stemborer moth ( considered the most important insect pest of maize at altitudes of 500m above sea level in sub-Saharan Africa)and the parasitic weed Striga, by the addition of a legume called Desmodium and a fodder plant,Napier grass, to the fields.
Desmodium is planted between the rows of maize, and produces volatile compounds to repel the Stemborer moth (the ‘push’ part of the system). It also produces compounds that induce Striga to germinate too early, before the maize has roots that are sufficiently developed for parasitism, and so the Striga dies off before it is able to establish itself. Additionally,as if this twin pest prevention wasn’t enough, Desmodium fixes much needed nitrogen into the soil and so also acts as a fertiliser. Napier grass (the ‘pull’ component), on the other hand, is planted at the edge of the crop, where is attracts the Stemborer moths to lay their eggs, yet prevents the Stemborer larvae from growing to adulthood. Furthermore, both Desmodium and Napier grass have value as fodder crops.
This system has already proved effective in the field, with one family even saying that it increased their yields from just 5 bags of maize to 35! This means they are no longer reliant upon charity handouts, and have been able to use their profits to re-roof their house and send their son to school.
What is brilliant this about this effective system is its simplicity. Once a few families have been shown the benefits of such a system and seen the effect on their own yields, it is easy for them to teach others.In short, the movement becomes self-sustaining. Yet it is not only subsistence farmers that can benefit from such systems. We should be trying to integrate techniques such as these into our energy intensive Western farming techniques, in a bid to make them more sustainable. Organic farming may have been invented by hippies, but we all need it now.
For more information, and success stories: http://www.rothamsted.ac.uk/Content/index-Section=ForThePublic&Page=GoodCompanions.html
And for more information on the Stem Borer: http://maizedoctor.cimmyt.org/en/component/content/310?task=view