Eighty percent of the food consumed in developing countries is produced by smallholder farmers, so it is critical that innovations are adapted to the needs of these farmers. Photo: © Sanjayan Muttulingam / TNC
By Eleanor Sterling and Erin Betley, Center for Biodiversity and Conservation, American Museum of Natural History
One year ago, we and our colleagues at the American Museum of Natural History in New York City opened a groundbreaking special exhibition Our Global Kitchen: Food, Nature, Culture, that took a systems view of the past, present, and future of food.
In the course of developing the exhibition, we were constantly confronted by some of the most challenging issues of our time — from food insecurity to the environmental impact of agriculture — and we were struck by an underlying question that connected so many of these issues: how can we feed humanity while also addressing biodiversity conservation?
Often these discussions focus on yield and how much more can we produce sustainably, but there is so much more to consider: how food is unevenly distributed regionally and around the world, how much food is wasted, the nutritional diversity of the food we produce, and the environmental impact of the food we eat, to name just a few key concerns.
We know that agriculture is dependent on often undervalued ecosystem services, from pollination to nutrient cycling (Power 2010, Wratten et al. 2013) and we know that there is a lively debate in the conservation community about the relative costs and benefits of protecting natural habitats from conversion to agriculture (known as “land-sparing”) or of maintaining biodiversity along with high yielding agriculture through diversified farming practices (known as “land-sharing”) (Phalan et al 2011; Kremen and Miles 2012).
Each approach encompasses complex tradeoffs, and economic, social, and political factors are at play in decisions about agriculture at all scales.
We noted in our research that many people on either side of the debate expected solutions to come from innovation through high technology.
As we read case after case and considered each approach, we asked ourselves, what if we could improve our food supply by taking lessons from nature rather than continually struggling against it?
For millennia, farmers have been keen observers of nature and natural cycles, constantly innovating to improve their crops and overcome challenges, creating a rich traditional ecological knowledge base. Are there examples of the intersection between this type of approach, and advanced modern innovation?
We found that a partnership of Kenyan farmers and scientists has implemented an innovative diversified farm system of cereal farming called “push-pull technology” that draws on an extensive understanding of the relationship between predators and competitors for cereal.
The predators, stemborers that feed on cereal plants, are “pushed” away from a group of plants, desmodium (Desmodium spp.), planted among the cereal plants and “pulled” towards Napier grass (Pennisetum purpureum) planted at the edge of the field.
Both the push and pull of the system are driven by naturally-occurring volatile chemicals that the predators find repellent or attractive, respectively. The sticky Napier plants trap the pests and their eggs away from the crop. The desmodium roots also contain a chemical that helps control weeds that otherwise outcompete cereal plants.
The leguminous desmodium improves soil fertility through nitrogen fixation and erosion control, and both companion plants are high quality fodder for livestock.
This effective system was developed through years of in-depth studies exploring the chemical compositions of various candidate push and pull plants and the behavioral responses of the insects, combined with rigorous field trials and observation (Hassani et al. 2008).
More than 30,000 farmers in Africa have adopted push-pull technology and, while the labor inputs are high, the process triples crop yield while decreasing dependence on expensive external inputs (Khan et al. 2011).
The Food and Agriculture Organization of the United Nations estimates that 80% of the food consumed in developing countries is produced by smallholder farmers, so it is critical that innovations are adapted to the needs of these farmers (FAO 2011).
Many people have asked us: sure this technique works with small-to mid-sized farms, but we’ll need farms at all scales to feed the growing human population, so can this be scaled up?
The principles of push-pull technology represent a growing set of strategies called agroecological approaches or diversified farming systems that are applied across many scales (Kremen et al 2012; Scherr and McNeely 2008).
Essentially, these strategies call for a landscape-scale approach to managing agricultural systems, emphasizing diversity and the outputs from one element of a landscape serving as inputs to another.
For example, the strategy may be about including riparian buffers in the landscape to keep soil from running off the land into waterways, and also protect local and regional water quality.
It may be about understanding, through scientific study and also field observations, how integrated systems of mixed crops and livestock can cycle nutrients efficiently across the farm. Planning at the landscape scale also involves incorporating considerations of people and their livelihoods, including healthier diets and farmer autonomy.
We know that a robust food system will be a diverse one, as we face the fact that currently 40% of Earth’s ice-free land is already under cultivation (Foley et al 2011), and we confront the challenges of climate change; natural limits to cheap energy and resources; and, increasingly, globalized and integrated markets.
There is much promise in partnerships between farmers and scientists that draw from a base of natural observation to inform innovation. These observations are built on an awareness of surroundings and relationships between organisms, and can be a powerful tool to be deployed for our collective future.
Eleanor Sterling is the Director of the American Museum of Natural History’s Center for Biodiversity and Conservation. Erin Betley is Biodiversity Specialist at the Center.
Food and Agriculture Organization of the United Nations. 2011. Save and Grow: A Policy-maker’s Guide to the Sustainable Intensification of Smallholder Crop Production. From: http://www.fao.org/docrep/014/i2215e/i2215e.pdf.
Foley, J. et al. 2011. Solutions for a cultivated planet. Nature 478:337-342.
Hassanli, A., H. Herren, Z. R. Khan, J.A. Pickett, and C. M. Woodcock. 2008. Integrated pest management: the push–pull approach for controlling insect pests and weeds of cereals, and its potential for other agricultural systems including animal husbandry. Annual Review of Entomology 52: 375-400
Khan, Z, C. Midega, J. Pittchar, J. Pickett, and T. Bruce. 2011. Push-pull technology: a conservation agriculture approach for integrated management of insect pests, weeds and soil health in Africa. International Journal of Agricultural Sustainability 9(1): 162-170.
Kremen, C. and A. Miles. 2012. Ecosystem services in biologically diversified versus conventional farming systems: benefits, externalities, and trade-offs. Ecology and Society 17(4):40.
Kremen, C., A. Iles, and C. Bacon. 2012. Diversified farming systems; an agroecological, systems-based alternative to modern industrial agriculture. Ecology and Society 17(4):44.
Phalan, B., M. Onial, A. Balmford, and R. E. Green. 2011. Reconciling Food Production and Biodiversity Conservation: Land Sharing and Land Sparing Compared. Science 333: 1289-1291.
Opinions expressed on Cool Green Science and in any corresponding comments are the personal opinions of the original authors and do not necessarily reflect the views of The Nature Conservancy.